Re: Which Dec Emulation is the MOST useful and Versatile?

[Eric Smith via cctalk]

On Fri, Nov 3, 2017 at 6:07 PM, Paul Koning via cctalk <
cctalk@classiccmp.org> wrote:

> Could be.  Then again, today's main architectures are all decades old;
> they get refined but not redone.
>

I'm not sure whether you consider the 64-bit ARM architecture to be one of
"today's main architectures", though it's probably shipping in higher unit
volume than x86. Anyhow, the 64-bit ARM architecture is pretty much brand
new; it's not the 32-bit ARM architecture stretched to 64 bits.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Paul Koning via cctalk]

> On Nov 3, 2017, at 11:58 AM, allison via cctalk  wrote:
> 
> Emulation of another computer was important to two groups early on...
> designers
> that wanted to try new architecture and the result of evolution and
> retirement of
> hardware the need to run costly to develop programs for which source or the
> needed components had become extinct.  The latter I believe is more rampant
> since the mid 70s with machines getting replaced with bigger and faster
> at an
> ever increasing rate. 

Could be.  Then again, today's main architectures are all decades old; they get 
refined but not redone.

Emulation of new architectures on old ones goes back quite a long time.  I've 
seen a document from 1964, describing the emulation of the Electrologica X8 
(which came out around 1964) on its predecessor the X1 (which dates back to 
1958).  

paul

Re: Which Dec Emulation is the MOST useful and Versatile?

[allison via cctalk]

On 11/02/2017 08:18 PM, Fred Cisin via cctalk wrote:
> On Sun, 29 Oct 2017, Dave Wade via cctalk wrote:
>> I am not sure they invented computer emulation. I think that the concept
>> Emulation/Simulation is as old as, or perhaps even older than computing.
>
> Henry Ford is attributed with "car racing began 5 minutes after the
> second car was built."
> BUT, I'm not sure whether the second computer cared about emulating
> the first one.
>
>
Emulation of another computer was important to two groups early on...
designers
that wanted to try new architecture and the result of evolution and
retirement of
hardware the need to run costly to develop programs for which source or the
needed components had become extinct.  The latter I believe is more rampant
since the mid 70s with machines getting replaced with bigger and faster
at an
ever increasing rate.   That cycle is wound so tight now that if you can
buy it
its likely obsolete.  It is also part of the more computers being
available and
CPU cycles on them being cheaper back in the late 70s and into the 80s made
it useful to use them to get the work from the last machine useful to design
the next machine. 

Personal example:  Altair built and running by Jan 75 as an early adoptor.
less than a year and a half NS* Horizon.  Why?  First Z80 runs 8080 code,
it was faster, better hardware.   It ran deeper but thats the 30,000 ft
view of
change.  And so it went to faster, more memory till PDP-11 push that to
auxiliary role followed by my first 32bit VAX.  It would take 486DX/66 with
networking to dislodge that.   Fortunately the bigger faster could emulate
the older slower sufficiently to run the software that was of greater value.

So here we are...  WIN10 has to have emulation/visualization to run old
32bit
and earlier software as 64bit architecture gets in the way.  The only
reason
the system is 64 bit is replacement of a dead 32bit that was
satisfactory in
every way save for its now unobtainium.  So it goes

I'll bet that the Henry Ford comment was followed by a comment from
someone making a better car to beat the second one!  It also forgets the
market for used cars was born right then. 


Allison

RE: Which Dec Emulation is the MOST useful and Versatile?

[Dave Wade via cctalk]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Fred
Cisin
> via cctalk
> Sent: 03 November 2017 00:19
> To: General Discussion: On-Topic and Off-Topic Posts
> <cctalk@classiccmp.org>
> Subject: RE: Which Dec Emulation is the MOST useful and Versatile?
> 
> On Sun, 29 Oct 2017, Dave Wade via cctalk wrote:
> > I am not sure they invented computer emulation. I think that the
> > concept Emulation/Simulation is as old as, or perhaps even older than
> computing.
> 
> Henry Ford is attributed with "car racing began 5 minutes after the second
car
> was built."
> BUT, I'm not sure whether the second computer caared about emulating the
> first one.
> 
Fred

It was the other way round. So you know the second computer will be better
than the first, but you haven't built it yet, so you emulate it on the
first. It's a common technique and was used by the ENIAC team to emulate an
EDVAC type machine, IBM also used it extensively when developing new
hardware, especially 370/XA...

Dave

Re: Which Dec Emulation is the MOST useful and Versatile?

[Angelo Papenhoff via cctalk]

On 29/10/17, Noel Chiappa via cctalk wrote:
> Another fun KA10 fact: it used 'hardware subroutines' - i.e. a clock pulse
> would get to a certain point, and get conditionally diverted through some
> other circuitry, later to come back and continue where it left off. Whee!

When I was taking a look at the CDC 1604 lately (btw, sadly two documents
are missing on bitsavers) I saw pretty much the same thing. Something
would set a flip-flop, go through the memory sequence, and continue from
the point it left off. This reminded me of the PDP-6 immediately (which
I'm very familiar with because of a logic-level emulator and verilog
implementation I've written [1]). The indexing and indirection mechanism
was also very similar. I suspect Gordon Bell was inspired by this
machine a bit. I think I'll mail him about the 6 again...


aap

[1] https://github.com/aap/pdp6

Re: Which Dec Emulation is the MOST useful and Versatile?

[Paul Koning via cctalk]

> On Oct 31, 2017, at 5:59 PM, allison via cctalk  wrote:
> 
> ...FYI rope core was basically many
> transformers either with a wire
> in for the bit or wire around for the not bit.  The cores for rope
> didn't change magnetic state like
> coincident current cores of the bistable type as that allowed read write
> but was DRO (destructive
> read out with re-write) which is the more familiar core and why it had a
> shorter read time and a
> longer cycle time between reads.

Actually, that's not accurate.  Core rope memory (Apollo Computer style) does 
use memory cores.  You can find it described well on a web page by Brent 
Halpern that discusses that and other (transformer style) memories.  In core 
rope memory, the selected core has its state changed by the combined select 
currents, and then it delivers pulses to whichever sense lines are threaded 
through that core when the core is reset again.

The Electrologica X1 has a core ROM that also uses memory cores, but in a 
different way than core rope.

paul

Re: Which Dec Emulation is the MOST useful and Versatile?

[Chuck Guzis via cctalk]

On 10/30/2017 03:44 PM, Paul Koning wrote:

> The timing is carefully orchestrated, including of course provision 
> for cable delays.
I'm reminded of a unit manager at CDC that I worked with for a time.
His first job at CDC as a fresh EE out of UofMinn was to measure all the
loops of cable on the backplane of the then-new 6600 to which Seymour
had attached tags that read "TUNE".

One marvels at the fiddling that must have been involved getting the
thing to run.  Fun with taper pins...

Cray was certainly a character.  Another associate regaled us with his
experience outside Seymour's lab in Chippewa Falls, sitting with a
couple of others in a car on a cold dark winter night exchanging code
and listings with Cray's daughter at the door.  He was not about to let
them inside...

--Chuck

Re: Which Dec Emulation is the MOST useful and Versatile?

[allison via cctalk]

On 10/30/2017 12:43 PM, Paul Koning via cctalk wrote:
>> On Oct 27, 2017, at 5:00 PM, Phil Blundell via cctalk 
>>  wrote:
>>
>> On Fri, 2017-10-27 at 13:38 -0700, Brent Hilpert via cctalk wrote:
>>> I wonder if they were just trying to draw an analogy between the
>>> inherent dynamic operation requirements of magnetic logic and the
>>> dynamic operation requirements of some (many?) NMOS designs (not
>>> really inherent to NMOS).
>> On the subject of NMOS dynamic logic, someone recently pointed out a
>> paragraph in the technical manual for a 1990s ARM2-based computer which
>> warned of dire consequences, including possibly destruction of the
>> chipset, if the circuitry was left powered with the clock stopped for
>> more than a second or two.
>>
>> Obviously if the clock is stopped for more than a few hundred
>> microseconds then the logic will start to lose its marbles and the
>> system will need a reset to recover.  But I don't think I've previously
>> heard any suggestion that dynamic logic ICs would actually be damaged
>> or destroyed under these circumstances.  I can just about imagine that
>> there might be some situation where an invalid internal state would
>> result in a short circuit between power and ground, but that's just
>> supposition really.  Anybody know of a case where something bad has
>> actually happened?
> I don't understand this at all.  "Dynamic logic" is not a familiar concept, 
> and certainly the NMOS logic I know isn't dynamic.  Memory (DRAM) is dynamic, 
> and will forget if you don't refresh it.  But DRAM doesn't mind if you stop 
> the clock, it just won't remember its data.
>
> So I don't know how you might have a logic design that "loses its marbles" if 
> you stop the clock.  And anything that is fried by clock loss is, in my view, 
> the work of someone who should not be allowed anywhere near a EE shop.

NMOS dynamic logic relies on two things memory or register cells that
operate just like
Dram so they forget without refresh.  It also relies on logic nodes that
precharge to some
state and are selectively discharged by the logic.  Doing that saves
resistive pullups or
complementary logic.  This type of logic has a specified minimum clock
though you
could usually go far slower.  The 8080 was an early example.

> Incidentally, while "soft core" magnetic logic is dynamic, memory core logic 
> is not.  You could slow that down and it would still work.  The signals are 
> pulses, not levels, but the pulses will still happen with a 1 Hz clock.
The timing of the logic in some cases where tied to the switching time
of the cores used.  Otherwise
it was hard to determine when and if the core switched.

However rope core and ferro-transformers would work at any rate so long
as the pulse waveform was
had the right rise and fall times.    FYI rope core was basically many
transformers either with a wire
in for the bit or wire around for the not bit.  The cores for rope
didn't change magnetic state like
coincident current cores of the bistable type as that allowed read write
but was DRO (destructive
read out with re-write) which is the more familiar core and why it had a
shorter read time and a
longer cycle time between reads.

Both have a fair amount of documentation out there.  The
ferro-transformer logic were documented
well too but you have to hunt for info.  They also came in many forms as
to the logic performed
including storage.


Allison

>   paul
>

CDC 6000 series transistors [was RE: Which Dec Emulation is the MOST useful and Versatile?]

[Rich Alderson via cctalk]

From: Paul Koning
Sent: Friday, October 27, 2017 12:07 PM

> True if you have a TTL machine.  6600 is discrete transistor, and the actual
> transistor specs are nowhere to be found as far as I have been able to tell.

> But that doesn't directly relate to gate level emulation.  If you have gate
> level documentation you can of course build a copy of the machine out of
> actual gate-type parts, like 7400 chips.  Or you can write a gate level model
> in VHDL, which is not the most popular form but certainly perfectly
> straightforward.  Either way, though, you have to start with a document that
> shows what the gates are in the original and how they connect.  And to get it
> to work, you need to deal with timing issues and logic abuse, if present.  In
> the 6600, both are very present and very critical.  For example, I've been
> debugging a section (the central processor branch logic) where the behavior
> changes quite substantially depending on whether you favor S or R in an R/S
> flop, i.e., if both are asserted at the same time, who wins?  And the circuit
> and wire delays matter, down to the few-nanosecond level.

Paul,

I asked the Principal Engineer here, who has spent the last 3 years making our
6500 run, about transistors in the 6000 series.  He replied:

Near as I can tell, the 6500 uses 2n2369 transistors in a slightly shorter
version of the to-18 package. I have had good success with both the 2n2369
for replacements, and mmbt2369 for the modules I have re-manufactured.

Since the flip-flops are merely cross coupled transistors, if they are both
set at once, both outputs will be true. In my experience, the set and reset
run on different phases of the clock, so that doesn't happen.

What you see on the logic diagrams can be interpreted this way: Each arrow
is a transistor, with the emitter tied to ground. The base usually has
about a 150 ohm resistor. The circle or square is the collector pull-up
resistor, so in the example of the PC module in 1n15 of the 6500, there are
two gates that can set flip-flop 0, and they come in on transistor 15, and
17, and the other side of the flip-flop comes in on transistor 19. All
three transistor collectors are connected together to 1 pull-up. If the
output pin does not go anywhere internal to the card, there will be a 120
ohm resistor in series with a diode to ground on it. If it does go
somewhere internal to the card, they will leave off the resistor/diode, as
the load will provide it.

Hope that helps.

Rich


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computers: Museum + Labs
2245 1st Avenue S
Seattle, WA 98134

mailto:ri...@livingcomputers.org

http://www.LivingComputers.org/

Re: Which Dec Emulation is the MOST useful and Versatile?

[Chuck Guzis via cctalk]

On 10/30/2017 04:18 AM, Eric Smith via cctalk wrote:

> 2. What a UTM does is simulate another machine using only a general-purpose
> machine. In fact, the UTM is arguably the most general-purpose machine ever
> described. What IBM defined as emulation was use of extremely specialized
> hardware and/or microcode (specifically, not the machine's general-purpose
> microcode used for natively programming the host machine). If anyone else
> did _that_ in a product before IBM, I'm very interested.

Well, "emulate" is a very fuzzy word, even in the context that you provide.

Taking as an example, some pre-S/360 hardware that's easily verified, is
the IBM 7094.   It ran the instruction set of the 7090 but with a single
departure--the use of 7 index registers, selectable using a 3-bit
isntruction field.  In the 7090, that same field selected any of three
registers--if you selected more than one, the contents were ORed
together before subtracting from the base address.   The 7094 did have a
"7090 compatibility mode" that used only the first three index registers
in the same manner as the 7090.

Specific hardware than enabled one machine to act as another.

So, is that "7090 emulation" on a 7094?

--Chuck

RE: Which Dec Emulation is the MOST useful and Versatile?

[Dave Wade via cctalk]

Eric,

 

The folks who made ENIAC programable didn’t use the word “program” but they ran 
what we would now call programs. The fact that the word wasn’t used doesn’t 
mean the concept hadn’t already been invented. I did check and Turing didn’t 
use the term in his paper “On Computable Numbers” and whilst the work “emulate” 
is now associated with Universal Turing Machines I am inclined to agree that 
Turing probably didn’t see this as “Emulation” in the modern sense of the word, 
but to me, there seems to be little difference between a UTM and SIMH….

 

Returning to ENIAC if you read Mark Priestley & Thomas Haig’s paper

 

http://eniacinaction.com/docs/AddressableAccumulators.pdf

 

you can see they describe ENIAC in stored program mode as “a microcoded 
interpreter for a virtual von Neumann architecture machine” which seems to me 
to be equivalent to what IBM did, some years earlier. 

When I spoke to Mark Priestley after the talk..

 

http://www.computerconservationsociety.org/lectures/2015-16/20160511.htm

 

he was quite clear that they configured ENIAC to emulate an EDVAC style machine 
and used the word “emulate” several times in the talk, so I would argue that 
the ENIAC pioneers invented the concept but did not name it as such…

 

Dave

 

 

 

 

From: Eric Smith [mailto:space...@gmail.com] 
Sent: 30 October 2017 11:18
To: General Discussion: On-Topic and Off-Topic Posts <cctalk@classiccmp.org>; 
Dave Wade <dave.g4...@gmail.com>
Subject: RE: Which Dec Emulation is the MOST useful and Versatile?

 

On Oct 29, 2017 09:54, "Dave Wade via cctalk" <cctalk@classiccmp.org 
<mailto:cctalk@classiccmp.org> > wrote:

I am not sure they invented computer emulation. I think that the concept
Emulation/Simulation is as old as, or perhaps even older than computing.
Whilst it was a pure concept Alan Turing's "Universal Turing Machine" was a
Turing machine that could emulate or simulate the behaviour of any arbitrary
Turing machine...

 

1. Did Turing use the word "emulate"? I honestly have no idea. My (possibly 
wrong) impression was that no published literature used the word emulate with 
that meaning (one computer emulating another) before the IBM papers.

 

2. What a UTM does is simulate another machine using only a general-purpose 
machine. In fact, the UTM is arguably the most general-purpose machine ever 
described. What IBM defined as emulation was use of extremely specialized 
hardware and/or microcode (specifically, not the machine's general-purpose 
microcode used for natively programming the host machine). If anyone else did 
_that_ in a product before IBM, I'm very interested.

 

 

 

Re: Which Dec Emulation is the MOST useful and Versatile?

[Jon Elson via cctalk]

On 10/30/2017 06:18 AM, Eric Smith via cctalk wrote:

2. What IBM defined as emulation was use of extremely specialized
hardware and/or microcode (specifically, not the machine's general-purpose
microcode used for natively programming the host machine).
As far as I know, IBM's 360s did NOT have any special 
purpose hardware associated with their emulation packages.
The only thing special was that additional microcode cards 
were installed.  In the 360/30, these were Mylar cards with 
word lines on them, they were punched on a card punch to 
punch out the capacitor plates to make zeroes.
On the 360/40, they were Mylar "tapes" that were punched to 
cut traces to go through or bypass the sense transformers.
On 360/50 and 65, they were etched word line boards that had 
traces that weaved under the bit line capacitor plates.
So, these were all custom to fit the specific instruction 
set to be emulated.  But, as far as I know, they added no 
additional logic to the machine to support the emulation.  
In some cases, this made things fairly inefficient.  At 
least on the 360/30, when running 14xx emulation, there were 
many holes in memory, because they did not convert between 
decimal and binary addresses.  So, memory locations 0-9 were 
used, A-F were inaccessible, 10-19 were used, 1A-1F were 
skipped, and so on.  Some of this made I/O buffers kind of 
strange, as the I/O buffers had to be repacked between the 
real I/O devices and the emulator's buffers.


Jon

RE: Which Dec Emulation is the MOST useful and Versatile?

[Eric Smith via cctalk]

On Oct 29, 2017 09:54, "Dave Wade via cctalk"  wrote:

I am not sure they invented computer emulation. I think that the concept
Emulation/Simulation is as old as, or perhaps even older than computing.
Whilst it was a pure concept Alan Turing's "Universal Turing Machine" was a
Turing machine that could emulate or simulate the behaviour of any arbitrary
Turing machine...


1. Did Turing use the word "emulate"? I honestly have no idea. My (possibly
wrong) impression was that no published literature used the word emulate
with that meaning (one computer emulating another) before the IBM papers.

2. What a UTM does is simulate another machine using only a general-purpose
machine. In fact, the UTM is arguably the most general-purpose machine ever
described. What IBM defined as emulation was use of extremely specialized
hardware and/or microcode (specifically, not the machine's general-purpose
microcode used for natively programming the host machine). If anyone else
did _that_ in a product before IBM, I'm very interested.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Johnny Eriksson via cctalk]

Lars Brinkhoff wrote:

> Jon Elson wrote:
> > I'm not sure the original DEC PDP-10 (KA-10) used microcode, but the
> > KI-10 did.
> 
> As far as I understand, the PDP-6 (type 166), KA10, and KI10 were
> hardwired.  KL10 and KS10 were microcoded.  The Foonly F1 preceeded and
> influenced the KL10 design.

This is exactly correct.

BTW: they still are...

--Johnny

Re: Which Dec Emulation is the MOST useful and Versatile?

[Jon Elson via cctalk]

On 10/28/2017 09:09 PM, Eric Smith via cctech wrote:

IBM invented computer emulation and introduced it with System/360 in 1964.
They defined it as using special-purpose hardware and/or microcode on a
computer to simulate a different computer.
Maurice V. Wilkes wrote a paper in 1951 defining 
microprogramming. IBM was not the first company to build 
machines using the technique.  They did make microcode 
mainstream technology with the 360, however.


Jon

RE: Which Dec Emulation is the MOST useful and Versatile?

[Dave Wade via cctalk]

Folks,
 Well I have now found one of Crispin Rope and Mark Priestly's papers on
ENIAC

http://eniacinaction.com/docs/AddressableAccumulators.pdf

It says

"ENIAC's original control method was modified in 1948, after which point its
wires and switches were left mostly untouched while it ran only a single
(but slowly evolving) program: a microcoded interpreter for a virtual von
Neumann architecture machine."

And 

"ENIAC's application programs were written as a series of two digit
instruction codes for this virtual machine and loaded into its read-only
function table memory by turning knobs to set digits."

I would therefore argue that "emulation" is as old as computing itself...

Dave Wade
G4UGM


> -Original Message-
> From: Dave Wade [mailto:dave.g4...@gmail.com]
> Sent: 29 October 2017 15:54
> To: 'Paul Koning' <paulkon...@comcast.net>; 'General Discussion: On-Topic
> and Off-Topic Posts' <cctalk@classiccmp.org>
> Subject: RE: Which Dec Emulation is the MOST useful and Versatile?
> 
> > -Original Message-
> > From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Paul
> > Koning via cctalk
> > Sent: 29 October 2017 12:42
> > To: Eric Smith <space...@gmail.com>; General Discussion: On-Topic
> > Posts <cct...@classiccmp.org>
> > Subject: Re: Which Dec Emulation is the MOST useful and Versatile?
> >
> >
> > > On Oct 28, 2017, at 10:09 PM, Eric Smith via cctech
> <cct...@classiccmp.org>
> > wrote:
> > >
> > > IBM invented computer emulation and introduced it with System/360 in
> > 1964.
> > > They defined it as using special-purpose hardware and/or microcode
> > > on a computer to simulate a different computer.
> >
> 
> I am not sure they invented computer emulation. I think that the concept
> Emulation/Simulation is as old as, or perhaps even older than computing.
> Whilst it was a pure concept Alan Turing's "Universal Turing Machine" was
a
> Turing machine that could emulate or simulate the behaviour of any
arbitrary
> Turing machine...
> 
> https://en.wikipedia.org/wiki/Universal_Turing_machine
> 
> .. and somewhat later when ENIAC was re-wired to execute programs stored
> in the function switchs, this was a partial simulation/emulation of EDSAC
> 
> https://en.wikipedia.org/wiki/ENIAC#Improvements
> 
> well that's what Crispin Rope asserts, but his book is still copyright and
I can't
> find any reference to this on the net,,
> 
> 
> > That's certainly a successful early commercial implementation of
> emulation,
> > done using a particular implementation approach.  At least for some of
> > the emulator features -- I believe you're talking about the 1401
emulator.
> IBM
> > didn't use that all the time; the emulator feature in the 360 model
> > 44, to emlulate the missing instructions, uses standard 360 code.
> >
> > It's not clear if that IBM product amounts to inventing emulation.  It
> seems
> > likely there are earlier ones, possibly not with that particular
> > choice of implementation techniques.
> >
> >
> > > Anything you run on your x86 (or ARM, MIPS, SPARC, Alpha, etc) does
> > > not meet that definition, and is a simulator, since those processors
> > > have only general-purpose hardware and microcode.
> > >
> > > Lots of people have other definitions of "emulator" which they've
> > > just pulled out of their a**, but since the System/360 architects
> > > invented it, I see no good reason to prefer anyone else's definition.
> >
> > "emulation" is just a standard English word.  I don't see a good
> > reason to
> limit
> > its application here to a specific intepretation given to it in a
> particular IBM
> > product.  It's not as if IBM's terminology is necessarily the
> > predominant
> one
> > in IT (consider "data set").  And in particular, as was pointed out
> before,
> > "emulator" has a quite specific (and different) meaning in the 1980s
> through
> > 2000 or so in microprocessor development hardware.
> >
> > paul
> Dave

Re: Which Dec Emulation is the MOST useful and Versatile?

[Noel Chiappa via cctalk]

> From: Jon Elson

> I'm not sure the original DEC PDP-10 (KA-10) used microcode

No, it didn't; in part because it pre-dated fast, cheap ROMs (the development
of which was a considerable task in the /360 project - the wonderful "IBM's
360 and Early 370 Systems" covers this is some detail). The KA10 is built out
of FLIP CHIPs which carried individual transistors.

Another fun KA10 fact: it used 'hardware subroutines' - i.e. a clock pulse
would get to a certain point, and get conditionally diverted through some
other circuitry, later to come back and continue where it left off. Whee!

Noel

Re: Which Dec Emulation is the MOST useful and Versatile?

[Lars Brinkhoff via cctalk]

Jon Elson wrote:
> I'm not sure the original DEC PDP-10 (KA-10) used microcode, but the
> KI-10 did.

As far as I understand, the PDP-6 (type 166), KA10, and KI10 were
hardwired.  KL10 and KS10 were microcoded.  The Foonly F1 preceeded and
influenced the KL10 design.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Jon Elson via cctalk]

On 10/29/2017 07:42 AM, Paul Koning via cctalk wrote:

On Oct 28, 2017, at 10:09 PM, Eric Smith via cctech  
wrote:

IBM invented computer emulation and introduced it with System/360 in 1964.
They defined it as using special-purpose hardware and/or microcode on a
computer to simulate a different computer.

That's certainly a successful early commercial implementation of emulation, 
done using a particular implementation approach.  At least for some of the 
emulator features -- I believe you're talking about the 1401 emulator.  IBM 
didn't use that all the time; the emulator feature in the 360 model 44, to 
emlulate the missing instructions, uses standard 360 code.
Except for certain machines (360/44, 360/91-95 series, model 
195) all other 360's were also emulated by microcode.
there really was no difference in running 360 code or 1401 
code on a 360 system, they were both done by microcode 
emulation.


The 360/44 had no control store, so any emulation/simulation 
had to be done by a program written in 360 instructions.
The 360/44 was a hardwired 360.  Note that while the 360 was 
a 32-bit instruction set, the 360/30 had only an 8-bit data 
path, and the 360/40 had only a 16-bit data path.

It's not clear if that IBM product amounts to inventing emulation.  It seems 
likely there are earlier ones, possibly not with that particular choice of 
implementation techniques.



Yes, there were others.  Burroughs and Univac also used 
microcode at about the same time.  I'm not sure the original 
DEC PDP-10 (KA-10) used microcode, but the KI-10 did.


Jon

Re: Which Dec Emulation is the MOST useful and Versatile?

[Jon Elson via cctalk]

On 10/28/2017 08:55 PM, Jay Jaeger via cctalk wrote:

On 10/27/2017 1:46 PM, ben via cctech wrote:

On 10/27/2017 9:27 AM, Jay Jaeger via cctech wrote:


With some FPGA venders you could get a TTL library components,
so you could input older designs. You may have to dig around for them
because that is not a NEW selling feature any more. Also logic
cells don't have asynchronous  set and clear anymore.

Ben.


I suppose, though writing a little HDL to provide the function of a TTL
gate isn't very hard.
Xilinx ise package provides a library of hundreds of 74xx 
TTL parts in schematic form, with VHDL code to provide the 
same functionality.  So, you can make up a schematic with 
74xx TTL parts, and then it instantiates the VHDL behavioral 
description of the part.  One could easily extract the VHDL 
from their library.


Jon

RE: Which Dec Emulation is the MOST useful and Versatile?

[Dave Wade via cctalk]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Paul
> Koning via cctalk
> Sent: 29 October 2017 12:42
> To: Eric Smith <space...@gmail.com>; General Discussion: On-Topic Posts
> <cct...@classiccmp.org>
> Subject: Re: Which Dec Emulation is the MOST useful and Versatile?
> 
> 
> > On Oct 28, 2017, at 10:09 PM, Eric Smith via cctech
<cct...@classiccmp.org>
> wrote:
> >
> > IBM invented computer emulation and introduced it with System/360 in
> 1964.
> > They defined it as using special-purpose hardware and/or microcode on
> > a computer to simulate a different computer.
> 

I am not sure they invented computer emulation. I think that the concept
Emulation/Simulation is as old as, or perhaps even older than computing.
Whilst it was a pure concept Alan Turing's "Universal Turing Machine" was a
Turing machine that could emulate or simulate the behaviour of any arbitrary
Turing machine...

https://en.wikipedia.org/wiki/Universal_Turing_machine

.. and somewhat later when ENIAC was re-wired to execute programs stored in
the function switchs, this was a partial simulation/emulation of EDSAC

https://en.wikipedia.org/wiki/ENIAC#Improvements

well that's what Crispin Rope asserts, but his book is still copyright and I
can't find any reference to this on the net,,


> That's certainly a successful early commercial implementation of
emulation,
> done using a particular implementation approach.  At least for some of the
> emulator features -- I believe you're talking about the 1401 emulator.
IBM
> didn't use that all the time; the emulator feature in the 360 model 44, to
> emlulate the missing instructions, uses standard 360 code.
> 
> It's not clear if that IBM product amounts to inventing emulation.  It
seems
> likely there are earlier ones, possibly not with that particular choice of
> implementation techniques.
> 
> 
> > Anything you run on your x86 (or ARM, MIPS, SPARC, Alpha, etc) does
> > not meet that definition, and is a simulator, since those processors
> > have only general-purpose hardware and microcode.
> >
> > Lots of people have other definitions of "emulator" which they've just
> > pulled out of their a**, but since the System/360 architects invented
> > it, I see no good reason to prefer anyone else's definition.
> 
> "emulation" is just a standard English word.  I don't see a good reason to
limit
> its application here to a specific intepretation given to it in a
particular IBM
> product.  It's not as if IBM's terminology is necessarily the predominant
one
> in IT (consider "data set").  And in particular, as was pointed out
before,
> "emulator" has a quite specific (and different) meaning in the 1980s
through
> 2000 or so in microprocessor development hardware.
> 
>   paul
Dave

Re: Which Dec Emulation is the MOST useful and Versatile?

[Chuck Guzis via cctalk]

An old kerfuffle over terms.

Speaking for myself, I use "emulate" when it involves human
characteristics.  "I seek to emulate Abraham Lincoln".

"Simulate" is probably a better term to use for inanimate objects.

I've never liked the e-word when used in connection with computers--but
I'm a traditionalist.


--Chuck

Re: Which Dec Emulation is the MOST useful and Versatile?

[Jay Jaeger via cctalk]

On 10/28/2017 9:09 PM, Eric Smith wrote:
> IBM invented computer emulation and introduced it with System/360 in
> 1964. They defined it as using special-purpose hardware and/or microcode
> on a computer to simulate a different computer.
> 
> Anything you run on your x86 (or ARM, MIPS, SPARC, Alpha, etc) does not
> meet that definition, and is a simulator, since those processors have
> only general-purpose hardware and microcode.
> 
> Lots of people have other definitions of "emulator" which they've just
> pulled out of their a**, but since the System/360 architects invented
> it, I see no good reason to prefer anyone else's definition.
> 

Well, I can think of a few.   From spending some time today with the IBM
360 catalog of programs for Model 25 and above (GC20-1619-8), IBM was
not entirely consistent with their terminology.

First of all, a lot of the products/applications that they called
emulators were in fact a *combination* of software with some microcode
hardware assist.  But they chose to call those emulators as well.  In
some of those cases, the emulated application could run side-by-side
with other S/360 programs, and in some cases not.

The ones I have spend the most time investigating over the years are
360C-EU-736 and 360-EU-738 - the 1410/7010 emulators.  I actually
tracked down the source code for one of those at one point (though I
don't remember which of the two, and where I stuck it at present).   I
think it was on one of the 360 DOS distributions available for use under
Hercules.  What I found was that it was almost all software, but with
hardware assist for the move and compare instructions.

>From the description in the catalog:

"DESCRIPTION - The 1710[sic]/7010 Emulator program is a stand-alone
program which, with the 1410/7010 Compatibility Feature (No. 4478) [ed.
- the microcode assist] executes 1410/7010 programs on a System/360
Model 50.  The Emulator program is an interpreter simulator that uses
both standard System/360 instructions ans special instructions provided
by the Compatibility feature..."

Secondly, your preferred use of the terms emulator and simulator seems
to go rather against the grain of how those terms are commonly applied
in English in general.  In ordinary English, the term emulation is
typically applied to observed *behavior*, whereas simulation is
typically applied to a more fine-grained reproduction of how that
behavior comes to be.  That is what led me down the exact opposite path
that you have gone down.  It was absolutely not, as you say, pulled out
of anyone's a**.  I and many others came to whatever definitions we use
with a fair amount of thought.

Finally, this was IBM's use of these terms of art from a long long time
ago, and to borrow from your words, I "see no good reason" to be
particularly bound by them.

The reality is that without some kind of body which would provide
specific definitions, such as those in the legal and medical
professions, this discussion is endless and the waters sufficiently
muddy as to be opaque.

JRJ

Re: Which Dec Emulation is the MOST useful and Versatile?

[Paul Koning via cctalk]

> On Oct 28, 2017, at 10:09 PM, Eric Smith via cctech  
> wrote:
> 
> IBM invented computer emulation and introduced it with System/360 in 1964.
> They defined it as using special-purpose hardware and/or microcode on a
> computer to simulate a different computer.

That's certainly a successful early commercial implementation of emulation, 
done using a particular implementation approach.  At least for some of the 
emulator features -- I believe you're talking about the 1401 emulator.  IBM 
didn't use that all the time; the emulator feature in the 360 model 44, to 
emlulate the missing instructions, uses standard 360 code. 

It's not clear if that IBM product amounts to inventing emulation.  It seems 
likely there are earlier ones, possibly not with that particular choice of 
implementation techniques.


> Anything you run on your x86 (or ARM, MIPS, SPARC, Alpha, etc) does not
> meet that definition, and is a simulator, since those processors have only
> general-purpose hardware and microcode.
> 
> Lots of people have other definitions of "emulator" which they've just
> pulled out of their a**, but since the System/360 architects invented it, I
> see no good reason to prefer anyone else's definition.

"emulation" is just a standard English word.  I don't see a good reason to 
limit its application here to a specific intepretation given to it in a 
particular IBM product.  It's not as if IBM's terminology is necessarily the 
predominant one in IT (consider "data set").  And in particular, as was pointed 
out before, "emulator" has a quite specific (and different) meaning in the 
1980s through 2000 or so in microprocessor development hardware.

paul

Re: Which Dec Emulation is the MOST useful and Versatile?

[Eric Smith via cctalk]

IBM invented computer emulation and introduced it with System/360 in 1964.
They defined it as using special-purpose hardware and/or microcode on a
computer to simulate a different computer.

Anything you run on your x86 (or ARM, MIPS, SPARC, Alpha, etc) does not
meet that definition, and is a simulator, since those processors have only
general-purpose hardware and microcode.

Lots of people have other definitions of "emulator" which they've just
pulled out of their a**, but since the System/360 architects invented it, I
see no good reason to prefer anyone else's definition.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Jay Jaeger via cctalk]

On 10/27/2017 1:46 PM, ben via cctech wrote:
> On 10/27/2017 9:27 AM, Jay Jaeger via cctech wrote:
> 
> 
> With some FPGA venders you could get a TTL library components,
> so you could input older designs. You may have to dig around for them
> because that is not a NEW selling feature any more. Also logic
> cells don't have asynchronous  set and clear anymore.
> 
> Ben.
> 

I suppose, though writing a little HDL to provide the function of a TTL
gate isn't very hard.  As it turns out, the design I replicated from my
college days was actually DTL, rather than TTL.  The lab consisted of 4
19" racks with interconnecting, differentially driven cables.  Each rack
had a card cage, and interconnections were done using re-purposed IBM
unit-record plugboards.  The current project, the IBM 1410, was
originally designed using IBM SMS - discrete transistors.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Chuck Guzis via cctalk]

On 10/27/2017 04:55 PM, Mike Stein via cctalk wrote:

> Or Burroughs' core counters (think I still have some somewhere):
> 
> https://www.google.com/patents/US3438014
> 
> http://www.freepatentsonline.com/2995663.html

We forget about all of the alternative ways of implementing digital
logic.  At one time, magnetic core logic was viewed as being much more
reliable than either tube or transistor logic, although not as fast.

Probably better hardened to radiation, as well.

In some respects, core logic reminds me somewhat of the McCulloch-Pitts
TLU model described in Minsky's book on Computation:

http://www.i-programmer.info/babbages-bag/325-mcculloch-pitts-neural-networks.html

--Chuck

Re: Which Dec Emulation is the MOST useful and Versatile?

[Mike Stein via cctalk]

- Original Message - 
From: "Chuck Guzis via cctalk" <cctalk@classiccmp.org>
To: <cctalk@classiccmp.org>
Sent: Friday, October 27, 2017 5:05 PM
Subject: Re: Which Dec Emulation is the MOST useful and Versatile?


> On 10/27/2017 01:39 PM, Al Kossow via cctalk wrote:
>> 
>> 
>> On 10/27/17 12:57 PM, Paul Koning wrote:
>> 
>>> That doesn't sound even close.
>> 
>> http://www.ussc90.nl/circ.htm
>> 
>> 
>> Ferractors.
>> 
> 
> Can't forget Parametrons:
> 
> https://www.thocp.net/hardware/parametron.htm
> 
> http://museum.ipsj.or.jp/en/heritage/NEAC-1101.html
> 
> --Chuck
>

Or Burroughs' core counters (think I still have some somewhere):

https://www.google.com/patents/US3438014

http://www.freepatentsonline.com/2995663.html

m

Re: Which Dec Emulation is the MOST useful and Versatile?

[ben via cctalk]

On 10/27/2017 9:27 AM, Jay Jaeger via cctech wrote:


With respect to your #5, I have some direct experience with that, and am
working on a tricky project to implement the IBM 1410 in a FPGA at the
gate level, based on the SMS Automated Logic Diagrams (ALD's).   What I
have found so far is that a rule or two can be used to deal with the
speed and design technology differences.  I don't think that the issues
pointed out make it "hard", really.  The hard part, to me, is
deciphering the original design from drawings or other incomplete
engineering information.  ;)  The rules I have developed so far:

a.  If the original implementation uses cross-connected gates (or
 transistors), the FPGA model can follow those with a synchronous D
 flip flop.  It usually works because the clock times are often 10
 or more times faster or more than the original machine clock.  I
 have successfully used this technique to implement an original
 design that was not all that great (see "b." below for details) that
 actually had some race conditions in the original design.

 The information on this project can be found at:

 https://drive.google.com/open?id=0B2v4WRwISEQRcFpNM0o2VDJiWFk

b.  I did not come across delays in the one project I completed
 this way (a re-implementation of a design done for a class in
 college in 1973), but my next project will, and my plan is to use a
 counter (or, I suppose, a small number of cascaded D flip flops
 acting as a bucket brigade) in cases where that delay is needed for
 the implementation to work properly.  (In cases where the delay
 exists only to match propagation times along different wire/cable
 lengths in the original implementation, one might be able to turn
 the delay into a wire).

JRJ


With some FPGA venders you could get a TTL library components,
so you could input older designs. You may have to dig around for them
because that is not a NEW selling feature any more. Also logic
cells don't have asynchronous  set and clear anymore.

Ben.

RE: Which Dec Emulation is the MOST useful and Versatile?

[Dave Wade via cctalk]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Chuck
> Guzis via cctalk
> Sent: 27 October 2017 22:06
> To: cctalk@classiccmp.org
> Subject: Re: Which Dec Emulation is the MOST useful and Versatile?
> 
> On 10/27/2017 01:39 PM, Al Kossow via cctalk wrote:
> >
> >
> > On 10/27/17 12:57 PM, Paul Koning wrote:
> >
> >> That doesn't sound even close.
> >
> > http://www.ussc90.nl/circ.htm
> >
> >
> > Ferractors.
> >
> 
> Can't forget Parametrons:
> 
> https://www.thocp.net/hardware/parametron.htm
> 
> http://museum.ipsj.or.jp/en/heritage/NEAC-1101.html
> 
> --Chuck


The Elliot 803 used ferrite transformers as logic elements


https://en.wikipedia.org/wiki/Elliott_803

Dave

Re: Which Dec Emulation is the MOST useful and Versatile?

[Jay Jaeger via cctalk]

On 10/27/2017 3:54 AM, Dave Wade via cctech wrote:
> Kip,
>  I think "emulation" and "simulation" get used pretty much interchangeable.
> SIMH is touted a simulator, Hercules/390 as an emulator yet they are both
> programs that provide a "bare metal" machine via software on which an
> operating system can be installed. Neither make any attempt to reproduce the
> speed of the original CPU.
> 
> I am going to stick with "emulator" as I think of "simulation" as process
> whereby we can model some statistical or mathematical parameters e.g. how
> long the queues are in a supermarket, what time is high tide in Boston using
> only mathematics. Note this may involve a general purpose computer, or it
> may use specialist machines such as the Doodson-Lege Tidal Predictor 
> 
> http://www.ntslf.org/about-tides/doodson-machine
> 
> So to return to emulating other computers have at least  five different
> flavours...
> 
> 1. Functional Software Emulation where we match the functions but not the
> speed of operation using a program. SIMH and Hercules are such beasts
> For much work this is fine. Most software emulators take this approach.
> 
> 2. Cycle accurate Software Emulation/Simulation where we attempt to match
> both function and speed of the underlying hardware. This may be necessary
> for software which uses software loops to control say the speed of a UART. I
> If you want to use the simulator for historical research this may help. Some
> emulators can be switched to this mode when software needs it...
> 
> David Sharp's SSEM/Baby simulator is such a beast.
> http://www.davidsharp.com/baby/
> 
> 3. Behavioural  Hardware Emulation
> This is where we build a hardware implementation of a machine, but do not
> attempt to duplicate the exact detail of the logic or its speed of
> operation. Richard Stofer's IBM1130 in VHDL is such a project. 
> He doesn't have it available on the Web (I have a copy and have run it)
> There is a Flash video on the IBM1130.org site
> 
> 4. Cycle Accurate Behavioural Hardware Emulation 
> This is probably the most common approach to cycle accurate emulations.
> Because FPGA's typically run several times faster than the clock on legacy
> hardware, and they may contain high level function blocks, e.g. multipliers
> its often "relatively easy" to match the instruction times of a legacy CPU
> in an FPGA. 
> 
> My BabyBaby FPGA implementation of the SSEM FPGA is such a beast. It runs at
> the same speed as replica SSEM in MSI Manchester but internally it's a
> parallel implementation whereas the real Baby is a serial machine.
> https://hackaday.com/2016/01/06/babybaby-a-1948-computer-on-an-fpga/
> 
> 5. Gate Level Hardware Emulation
> It gate level hardware emulation we try and re-implement the hardware down
> to the logic gate level. This is hard because FPGA's are may not be designed
> to work this way, and gate level design will also have some dependencies on
> propagation delays, which on an FPGA will be much smaller than on any real
> hardware. A couple of examples of these are 
> 
> Laurence Wilkinson's IBM 360/30 http://www.ljw.me.uk/ibm360/
> Carl Claunch's IBM 1130 http://ibm1130.blogspot.co.uk/
> 
> I hope this doesn't muddy the water too much...
> Dave
>   

Well, the waters are sufficiently muddy that I figured little harm would
be dine if I throw my weeds in too...   ;)

I like that you have clearly given this some thought, and have developed
a kind of taxonomy, so your comments are valuable because they are not
just off-the cuff.

Looking online at Merriam-Webster, the conclusion one might reach is
that these are all simulators.  But emulation is also a term of art when
it comes to computers, so I don't think we should shackle ourselves to M-W.

I have generally used the term emulator for software that attempts to
provide some level of functionality (up to 100%) of the original machine
such that software (including operating systems) will operate, without
worrying about HOW that is done.  So, I would throw most, if not all, of
the SimH programs, and Hercules as well into that pot.  I would also put
the IBM 1401 and 1410 emulators that appeared on early model IBM
System/360 machines (which was done using software with microcode
assist) into that same bag, as well as the FLEX implementation of the
IBM mainframe architectures.  So, I am on the same page with you with
regards to #1.

I have generally used the term simulator for software that attempts to
replicate the actual operation of the original machine, regardless of
speed - I view speed as just one of several possible measures of the
accuracy/level of the simulation.  I have written an IBM 1410 simulator
that simulates the operation of the original machine at the machine
cycle level, based on the IBM CE instructional materials - but it pays
no attention at all to the absolute cycle time, only to the relative
cycle time (so that peripherals, such as tape drives, work in about the
same relative speed to the CPU as the 

Re: Which Dec Emulation is the MOST useful and Versatile?

[Al Kossow via cctalk]

On 10/27/17 2:00 PM, Phil Blundell via cctalk wrote:

> On the subject of NMOS dynamic logic, someone recently pointed out a
> paragraph in the technical manual for a 1990s ARM2-based computer which
> warned of dire consequences, including possibly destruction of the
> chipset, if the circuitry was left powered with the clock stopped for
> more than a second or two.
>

https://en.wikichip.org/wiki/acorn/microarchitectures/arm2

ARM2 chips were manufactured by VLSI Technology and Sanyo on a 2 µm 
double-level metal CMOS process.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Chuck Guzis via cctalk]

On 10/27/2017 01:39 PM, Al Kossow via cctalk wrote:
> 
> 
> On 10/27/17 12:57 PM, Paul Koning wrote:
> 
>> That doesn't sound even close.
> 
> http://www.ussc90.nl/circ.htm
> 
> 
> Ferractors.
> 

Can't forget Parametrons:

https://www.thocp.net/hardware/parametron.htm

http://museum.ipsj.or.jp/en/heritage/NEAC-1101.html

--Chuck

Re: Which Dec Emulation is the MOST useful and Versatile?

[ben via cctalk]

On 10/27/2017 1:06 PM, Paul Koning wrote:


True if you have a TTL machine.  6600 is discrete transistor, and the actual 
transistor specs are nowhere to be found as far as I have been able to tell.


Well if you can find one loose, you could allways measure it.


But that doesn't directly relate to gate level emulation.  If you have gate 
level documentation you can of course build a copy of the machine out of actual 
gate-type parts, like 7400 chips.  Or you can write a gate level model in VHDL, 
which is not the most popular form but certainly perfectly straightforward.  
Either way, though, you have to start with a document that shows what the gates 
are in the original and how they connect.  And to get it to work, you need to 
deal with timing issues and logic abuse, if present.  In the 6600, both are 
very present and very critical.  For example, I've been debugging a section 
(the central processor branch logic) where the behavior changes quite 
substantially depending on whether you favor S or R in an R/S flop, i.e., if 
both are asserted at the same time, who wins?  And the circuit and wire delays 
matter, down to the few-nanosecond level.


You need to find a lucky man, for help. You stand here, and look that 
way. Yes it works.






Most machines are not so crazy; I would assume a PDP-11/20 gate level model 
would be quite painless.

paul


I still have not figured out VHDL yet. Logic that I can figure out, but 
how you use the the stupid
logic blocks I can not with all the stupid type defines. What I need is 
real reference book, not a DUMMYS GUIDE TO BLA-BLA-BLA.


For my own hobby stuff I am useing WINCPUL and ALTERA's AHDL. There a D 
F/F is D flip flop.

Ben.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Phil Blundell via cctalk]

On Fri, 2017-10-27 at 13:38 -0700, Brent Hilpert via cctalk wrote:
> I wonder if they were just trying to draw an analogy between the
> inherent dynamic operation requirements of magnetic logic and the
> dynamic operation requirements of some (many?) NMOS designs (not
> really inherent to NMOS).

On the subject of NMOS dynamic logic, someone recently pointed out a
paragraph in the technical manual for a 1990s ARM2-based computer which
warned of dire consequences, including possibly destruction of the
chipset, if the circuitry was left powered with the clock stopped for
more than a second or two.

Obviously if the clock is stopped for more than a few hundred
microseconds then the logic will start to lose its marbles and the
system will need a reset to recover.  But I don't think I've previously
heard any suggestion that dynamic logic ICs would actually be damaged
or destroyed under these circumstances.  I can just about imagine that
there might be some situation where an invalid internal state would
result in a short circuit between power and ground, but that's just
supposition really.  Anybody know of a case where something bad has
actually happened?

p.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Chuck Guzis via cctalk]

On 10/27/2017 01:01 PM, Paul Koning wrote:

> Oh yes, and if you look at the wire lists (on Bitsavers) you will get the 
> length of every wire in the machine.  The trouble is that, even if you use 
> the documented delay per foot, things don't necessarily match.  The stated 
> logic stage delay is 5 ns, no special numbers given for twisted pair drivers. 
>  In my model, I do everything in 5 ns multiples (to keep the simulation time 
> under control).  That works pretty closely, but not 100 percent, not for some 
> of the CPU pieces.  The other thing that's nuts is that the CPU effectively 
> has a 20-phase clock: the documentation shows clock signals with offsets from 
> the reference time given in multiples of 5 nanoseconds (for the 100 ns clock 
> period).  And yes, it matters.  And yes, many (I'm not sure about all) of the 
> 20 phases are actually used in the CPU.

I can't recall, but didn't the 6600 have something like 10 clock
sources, all kept synchronized?

In any case, it's a gross oversimplification to say that the 6600 had a
10 MHz clock.


--Chuck

Re: Which Dec Emulation is the MOST useful and Versatile?

[Al Kossow via cctalk]

On 10/27/17 1:38 PM, Brent Hilpert via cctalk wrote:

> I wonder if they were just trying to draw an analogy between the inherent 
> dynamic operation requirements of magnetic logic and the dynamic operation 
> requirements of some (many?) NMOS designs (not really inherent to NMOS).

this was a long time ago, and it probably was comparing it to multiphase MOS 
clocking
this came from Mike Albaugh, who had a SS90 at one point.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Brent Hilpert via cctalk]

On 2017-Oct-27, at 12:57 PM, Paul Koning via cctalk wrote:
>> On Oct 27, 2017, at 3:21 PM, Al Kossow via cctalk  
>> wrote:
>> On 10/27/17 12:16 PM, Chuck Guzis via cctalk wrote:
>> 
>>> I've long had a fantasy about building a core-logic CPU such as the
>>> Univac Solid State.
>> 
>> I have been told the behavior of Univac magnetic logic was similar to NMOS
> 
> That doesn't sound even close.


It does seem like a strange statement.
I wonder if they were just trying to draw an analogy between the inherent 
dynamic operation requirements of magnetic logic and the dynamic operation 
requirements of some (many?) NMOS designs (not really inherent to NMOS).


> Ken Olsen did his thesis on magnetic core logic.  There is some (but 
> surprisingly little) information on line about this technology.  There are 
> two flavors: with permanent magnetic cores (memory cores) and with "soft" 
> cores (transformers).  Apollo "rope" core memory ROM is an example of the 
> former.
> 
>   paul

Re: Which Dec Emulation is the MOST useful and Versatile?

[Al Kossow via cctalk]

On 10/27/17 12:57 PM, Paul Koning wrote:

> That doesn't sound even close.

http://www.ussc90.nl/circ.htm


Ferractors.

While computers now are composed by many integrated circuits containing each 
millions of logical units,
processing data with a speed of a few gigabits per second in a parallel-flow of 
64 bits,
the USSC's CPU-logic was composed of over 1000 circuit boards with each only a 
few active components.
One circuitboard contained only 4 simple logical units, the ferractors.
These circuit-boards processed the data with the theoretical speed of 700 
KBits/second.
The ferractors were tiny transformers, performing one-bit operations, powered 
by 700 KCs AC.

On the positive half of the cycle, the ferractor-core was magnetised or not 
depending on the current through the bias-coil,
which made the total magnetic field in the core to exceed the 
hysteresis-threshold or not.
In the subsequent negative half-cycle the ferractor showed on the secondairy 
coil a high or a low impedance,  depending
on whether it had been magnetised or not.
On low-impedance a positif bias-current was generated for the next 
ferractor-circuit.

Since each ferractor was set in one cycle-half and was read in the next 
cycle-half, an one bit-stream of a register was
formed
by 24 ferractors in series, alternatingly fed by opposite phases.
In such a string of ferractor-circuits 12 bits cycled around, 10 bits, a sign 
and a space.
The information in the registers was circling around in 4 parallel 
one-bit-strings.
The data in the registers cycled around with the same speed as the information 
on the drum-memory.

The 200 diode-boards were used in OR and in NAND functions, depending on being 
located in the positive-phase-circuitry
or the negative-one.
The bias-coil was connected in positive or negative polarity to enforce or to 
diminish magnetisation during the first
half-cycle
in order to create normal or inverting logical gates.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Paul Koning via cctalk]

> On Oct 27, 2017, at 3:21 PM, Al Kossow via cctalk  
> wrote:
> 
> 
> 
> On 10/27/17 12:16 PM, Chuck Guzis via cctalk wrote:
> 
>> I've long had a fantasy about building a core-logic CPU such as the
>> Univac Solid State.
> 
> I have been told the behavior of Univac magnetic logic was similar to NMOS

That doesn't sound even close.

Ken Olsen did his thesis on magnetic core logic.  There is some (but 
surprisingly little) information on line about this technology.  There are two 
flavors: with permanent magnetic cores (memory cores) and with "soft" cores 
(transformers).  Apollo "rope" core memory ROM is an example of the former.

paul

Re: Which Dec Emulation is the MOST useful and Versatile?

[Al Kossow via cctalk]

On 10/27/17 12:16 PM, Chuck Guzis via cctalk wrote:

> I've long had a fantasy about building a core-logic CPU such as the
> Univac Solid State.

I have been told the behavior of Univac magnetic logic was similar to NMOS
which explains why there is an RF power amplifier for the clock driver in
the machine.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Chuck Guzis via cctalk]

On 10/27/2017 12:06 PM, Paul Koning via cctalk wrote:

> But that doesn't directly relate to gate level emulation.  If you
> have gate level documentation you can of course build a copy of the
> machine out of actual gate-type parts, like 7400 chips.  Or you can
> write a gate level model in VHDL, which is not the most popular form
> but certainly perfectly straightforward.  Either way, though, you
> have to start with a document that shows what the gates are in the
> original and how they connect.  And to get it to work, you need to
> deal with timing issues and logic abuse, if present.  In the 6600,
> both are very present and very critical.  For example, I've been
> debugging a section (the central processor branch logic) where the
> behavior changes quite substantially depending on whether you favor S
> or R in an R/S flop, i.e., if both are asserted at the same time, who
> wins?  And the circuit and wire delays matter, down to the
> few-nanosecond level.

This.  In particular, google for a shot of the 6600 backplane.  Many of
those twisted wires were cut to provide specific delays.  Remember the
nanosecond-foot?  A lot of the old hardware used this in the design.

I've long had a fantasy about building a core-logic CPU such as the
Univac Solid State.  But heck if I know where one would get the "hard"
magnetic cores today.   Another example of something you can't do with
commodity TTL.


--Chuck

Re: Which Dec Emulation is the MOST useful and Versatile?

[Paul Koning via cctalk]

> On Oct 27, 2017, at 2:55 PM, ben via cctalk  wrote:
> 
> On 10/27/2017 12:28 PM, Paul Koning via cctalk wrote:
> 
>> It helps to have a machine built with sane design principles.  Things like 
>> RS flops that don't have both inputs active at the same time.  And a 
>> properly clocked architecture.  Neither of these properties holds for the 
>> CDC 6600...
>>  paul
> 
> But you can still get TTL for the common stuff,and PAL/GAL chips as well, so 
> nothing is preventing you from doing the common logic of
> the 1965 to 1985 era, if it not for production use.
> Ben.

True if you have a TTL machine.  6600 is discrete transistor, and the actual 
transistor specs are nowhere to be found as far as I have been able to tell.

But that doesn't directly relate to gate level emulation.  If you have gate 
level documentation you can of course build a copy of the machine out of actual 
gate-type parts, like 7400 chips.  Or you can write a gate level model in VHDL, 
which is not the most popular form but certainly perfectly straightforward.  
Either way, though, you have to start with a document that shows what the gates 
are in the original and how they connect.  And to get it to work, you need to 
deal with timing issues and logic abuse, if present.  In the 6600, both are 
very present and very critical.  For example, I've been debugging a section 
(the central processor branch logic) where the behavior changes quite 
substantially depending on whether you favor S or R in an R/S flop, i.e., if 
both are asserted at the same time, who wins?  And the circuit and wire delays 
matter, down to the few-nanosecond level.

Most machines are not so crazy; I would assume a PDP-11/20 gate level model 
would be quite painless.

paul

Re: Which Dec Emulation is the MOST useful and Versatile?

[Brent Hilpert via cctalk]

On 2017-Oct-27, at 11:28 AM, Paul Koning via cctalk wrote:
> It helps to have a machine built with sane design principles.  Things like RS 
> flops that don't have both inputs active at the same time.  And a properly 
> clocked architecture.  Neither of these properties holds for the CDC 6600...


True of a lot of 50s / 60s / even early-70s logic, designers took a lot of 
'electronic shortcuts' to save components, capacitive coupling for instance 
being popular.

Flip flops with half-a dozen options of semantically different input types 
which could be combined in multiple, so every flip-flop in the system was 
unique with it's particular set of (sometimes many) input options.

One logic design I encountered had a type of logic element specifically 
intended (from what I could figure) to soak up glitches.
It could take in multiple inputs with edges occurring at slightly skewed times 
and ensured that only one slightly-delayed edge would be propagated out.

Re: Which Dec Emulation is the MOST useful and Versatile?

[ben via cctalk]

On 10/27/2017 12:28 PM, Paul Koning via cctalk wrote:


It helps to have a machine built with sane design principles.  Things like RS 
flops that don't have both inputs active at the same time.  And a properly 
clocked architecture.  Neither of these properties holds for the CDC 6600...

paul


But you can still get TTL for the common stuff,and PAL/GAL chips as 
well, so nothing is preventing you from doing the common logic of

the 1965 to 1985 era, if it not for production use.
Ben.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Noel Chiappa via cctalk]

> From: Kip Koon

> I tend to get emulation and simulation a bit confused. 

You and me both!

I think part of the problem is that there is no generally-agreed-upon
definition of the two terms.

I like this one a lot, though:

  
https://stackoverflow.com/questions/1584617/simulator-or-emulator-what-is-the-difference

  Emulation is the process of mimicking the outwardly observable behavior to
  match an existing target. The internal state of the emulation mechanism
  does not have to accurately reflect the internal state of the target which
  it is emulating.

  Simulation, on the other hand, involves modeling the underlying state of
  the target. The end result of a good simulation is that the simulation
  model will emulate the target which it is simulating. 

  Ideally, you should be able to look into the simulation and observe
  properties that you would also see if you looked into the original target.
  In practice, there may some shortcuts to the simulation for performance
  reasons -- that is, some internal aspects of the simulation may actually be
  an emulation.

  ...

  EDIT: Other responses have pointed out that the goal of an emulation is to
  able to substitute for the object it is emulating. That's an important
  point. A simulation's focus is more on the modelling of the internal state
  of the target - and the simulation does not necessarily lead to emulation.
  ... SPICE, for example, cannot substitue for an actual electronics circuit


There's also the question of what's being emulated.

Ersatz-11, for example, does a good job of looking like a PDP-11 - for the
software. However, it does not like a PDP-11 for the hardware (although John
used to sell boards you could plug into a PC, which provided a QBUS, IIRC).

So is it a simulator or an emulator? Good question.

About the only _generally-agreed_ example of the terminology I can think of
are 'in-circuit emulators', which _exactly_ match the behaviour of a given
chip.

Noel

Re: Which Dec Emulation is the MOST useful and Versatile?

[Brent Hilpert via cctalk]

On 2017-Oct-27, at 10:27 AM, Paul Koning via cctalk wrote:
> So it's a question of what you're after.  If you want to run the software, or 
> teach the machine at the programmer level, SIMH or equivalent is quite 
> adequate.  If you want to teach FPGA skills, an FPGA behavioral model 
> emulation is a good project, especially for a small machine like a PDP-8.  As 
> for the gate level model, I'm not sure what argument to make for that other 
> than "paul is a bit crazy" and "because the data exists to do it".  :-)

I would add that gate/logic level simulations in some instances can be useful 
if you have to understand and repair the original hardware.

Back in the 90s I was attempting to repair a 60s-era SSI-based calculator, I 
reverse-engineered it but was still stuck with issues of access
to the PC boards, understanding the design, having to hack up the PCB traces or 
unsolder (unobtainable) ICs.
I resorted to writing a logic simulator (in a high-level scripting language) 
and entering the 'net list' of the reverse-engineered logic to
produce a gate-level simulation.
I could then play around with the simulator, slow the clock to observable 
rates, monitor any and multiple points, break connections,
force logic levels, eventually to obtain the same fault as the real hardware.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Paul Koning via cctalk]

> On Oct 27, 2017, at 1:47 PM, Rob Jarratt  wrote:
> 
> If I had the skill, data and time, I would always go for a gate level model.
> However, I do most (sim/em)ulation in SIMH instead, like I have been doing
> for MU5 where I lack the data and the time and probably the skill as well,
> but I can always acquire the skill, the other two are harder to find.

I've read some VHDL before, but my 6600 gate level model was my first VHDL 
project.  It's actually quite easy, easier than the level of fluency needed to 
do a good behavioral model.  A decent textbook helps a lot.  My favorite is The 
Designer's Guide to VHDL by Peter Ashenden.  The point is that modeling small 
modules (SSI gates, or 6600 "cordwood" modules, or the like) is easy because 
they are small and have quite simple behavior.  Then it's just a matter of 
wiring them together.

Note that you don't need an FPGA to do logic level design; all you need is a 
VHDL simulator.  I use GHDL, which is open source, part of GCC so you can hook 
in C code if you need it.  For example, that allows you to make a model of the 
I/O channel and connect it to a SIMH style emulation of a peripheral device.

The real issue for gate level modeling is the availability of the necessary 
documentation.  If you have schematics, and they includes critical detail such 
as microcode ROM contents, you're all set.  If all you have is functional 
specs, you can't even start.

It helps to have a machine built with sane design principles.  Things like RS 
flops that don't have both inputs active at the same time.  And a properly 
clocked architecture.  Neither of these properties holds for the CDC 6600...

paul

RE: Which Dec Emulation is the MOST useful and Versatile?

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Paul
Koning
> via cctalk
> Sent: 27 October 2017 18:28
> To: Dave Wade <dave.g4...@gmail.com>; General Discussion: On-Topic and
> Off-Topic Posts <cctalk@classiccmp.org>
> Subject: Re: Which Dec Emulation is the MOST useful and Versatile?
> 
> 
> > On Oct 27, 2017, at 4:54 AM, Dave Wade via cctalk
<cctalk@classiccmp.org>
> wrote:
> >
> > Kip,
> > I think "emulation" and "simulation" get used pretty much
interchangeable.
> > SIMH is touted a simulator, Hercules/390 as an emulator yet they are
> > both programs that provide a "bare metal" machine via software on
> > which an operating system can be installed. Neither make any attempt
> > to reproduce the speed of the original CPU.
> 
> True.  And by some argument, an FPGA implementation (from an HDL
> behavioral model) is also a software implementation, just written in a
different
> programming language.
> 
> Recently I commented to an old colleague that there are many different
levels
> of emulation possible, and any one of those may make sense -- it's just a
> question of what you're after.  So you can emulate in a conventional
> programming language, as SIMH does, reproducing the programmer-visible
> behavior of the machine but not its timing.  Bugs from the original might
> appear if those bugs are known to be important, but probably not
otherwise.
> This kind is (nowadays) likely to run faster than the original; certainly
it won't
> usually mimic the original timing, neither for computation nor I/O.
> 
> You can make timing-accurate software emulators, with lots of work.  SIMH,
in
> paced mode, and provided the I/O waits are reasonably accurately expressed
in
> units of machine cycles, isn't quite timing accurate but is somewhat
similar.
> 
> You can build a behavioral simulator (SIMH style, basically) in an FPGA.
That
> isn't necessarily any more capable or accurate than a software simulator.
PDP-
> 2011 is an example I know of, and I've see articles about other PDP
emulations
> of this kind.  Since the design is new, created from a behavioral
description
> (data book, functional spec, architecture spec) it will be about as
accurate as
> SIMH.
> 
> You can also, if the data exists, build a lower level (gate level or
thereabouts)
> FPGA model.  Given schematics and wire lists, it should be possible to
build an
> implementation that's an exact copy of how the original machine worked
> (assuming of course the documentation is accurate, which is not
necessarily the
> case).  Such an emulation would replicate strange and undocumented
behavior
> of the original -- and allow you to find out where that came from.  I've
been
> working on such a thing for the CDC 6600, which is surprisingly hard given
that
> the design lives right on the hairy edge of not working at all
timing-wise.  But it
> does accuarately model the peripheral processors right now, and indeed it
> shows and explains some undocumented oddities that are part of that
> machine's folklore.
> 
> So it's a question of what you're after.  If you want to run the software,
or teach
> the machine at the programmer level, SIMH or equivalent is quite adequate.
If
> you want to teach FPGA skills, an FPGA behavioral model emulation is a
good
> project, especially for a small machine like a PDP-8.  As for the gate
level
> model, I'm not sure what argument to make for that other than "paul is a
bit
> crazy" and "because the data exists to do it".  :-)
> 


If I had the skill, data and time, I would always go for a gate level model.
However, I do most (sim/em)ulation in SIMH instead, like I have been doing
for MU5 where I lack the data and the time and probably the skill as well,
but I can always acquire the skill, the other two are harder to find.

Regards

Rob

Re: Which Dec Emulation is the MOST useful and Versatile?

[Paul Koning via cctalk]

> On Oct 27, 2017, at 4:54 AM, Dave Wade via cctalk  
> wrote:
> 
> Kip,
> I think "emulation" and "simulation" get used pretty much interchangeable.
> SIMH is touted a simulator, Hercules/390 as an emulator yet they are both
> programs that provide a "bare metal" machine via software on which an
> operating system can be installed. Neither make any attempt to reproduce the
> speed of the original CPU.

True.  And by some argument, an FPGA implementation (from an HDL behavioral 
model) is also a software implementation, just written in a different 
programming language.

Recently I commented to an old colleague that there are many different levels 
of emulation possible, and any one of those may make sense -- it's just a 
question of what you're after.  So you can emulate in a conventional 
programming language, as SIMH does, reproducing the programmer-visible behavior 
of the machine but not its timing.  Bugs from the original might appear if 
those bugs are known to be important, but probably not otherwise.  This kind is 
(nowadays) likely to run faster than the original; certainly it won't usually 
mimic the original timing, neither for computation nor I/O.

You can make timing-accurate software emulators, with lots of work.  SIMH, in 
paced mode, and provided the I/O waits are reasonably accurately expressed in 
units of machine cycles, isn't quite timing accurate but is somewhat similar.

You can build a behavioral simulator (SIMH style, basically) in an FPGA.  That 
isn't necessarily any more capable or accurate than a software simulator.  
PDP-2011 is an example I know of, and I've see articles about other PDP 
emulations of this kind.  Since the design is new, created from a behavioral 
description (data book, functional spec, architecture spec) it will be about as 
accurate as SIMH.

You can also, if the data exists, build a lower level (gate level or 
thereabouts) FPGA model.  Given schematics and wire lists, it should be 
possible to build an implementation that's an exact copy of how the original 
machine worked (assuming of course the documentation is accurate, which is not 
necessarily the case).  Such an emulation would replicate strange and 
undocumented behavior of the original -- and allow you to find out where that 
came from.  I've been working on such a thing for the CDC 6600, which is 
surprisingly hard given that the design lives right on the hairy edge of not 
working at all timing-wise.  But it does accuarately model the peripheral 
processors right now, and indeed it shows and explains some undocumented 
oddities that are part of that machine's folklore.

So it's a question of what you're after.  If you want to run the software, or 
teach the machine at the programmer level, SIMH or equivalent is quite 
adequate.  If you want to teach FPGA skills, an FPGA behavioral model emulation 
is a good project, especially for a small machine like a PDP-8.  As for the 
gate level model, I'm not sure what argument to make for that other than "paul 
is a bit crazy" and "because the data exists to do it".  :-)

paul

RE: Which Dec Emulation is the MOST useful and Versatile?

[Dave Wade via cctalk]

Kip,
 I think "emulation" and "simulation" get used pretty much interchangeable.
SIMH is touted a simulator, Hercules/390 as an emulator yet they are both
programs that provide a "bare metal" machine via software on which an
operating system can be installed. Neither make any attempt to reproduce the
speed of the original CPU.

I am going to stick with "emulator" as I think of "simulation" as process
whereby we can model some statistical or mathematical parameters e.g. how
long the queues are in a supermarket, what time is high tide in Boston using
only mathematics. Note this may involve a general purpose computer, or it
may use specialist machines such as the Doodson-Lege Tidal Predictor 

http://www.ntslf.org/about-tides/doodson-machine

So to return to emulating other computers have at least  five different
flavours...

1. Functional Software Emulation where we match the functions but not the
speed of operation using a program. SIMH and Hercules are such beasts
For much work this is fine. Most software emulators take this approach.

2. Cycle accurate Software Emulation/Simulation where we attempt to match
both function and speed of the underlying hardware. This may be necessary
for software which uses software loops to control say the speed of a UART. I
If you want to use the simulator for historical research this may help. Some
emulators can be switched to this mode when software needs it...

David Sharp's SSEM/Baby simulator is such a beast.
http://www.davidsharp.com/baby/

3. Behavioural  Hardware Emulation
This is where we build a hardware implementation of a machine, but do not
attempt to duplicate the exact detail of the logic or its speed of
operation. Richard Stofer's IBM1130 in VHDL is such a project. 
He doesn't have it available on the Web (I have a copy and have run it)
There is a Flash video on the IBM1130.org site

4. Cycle Accurate Behavioural Hardware Emulation 
This is probably the most common approach to cycle accurate emulations.
Because FPGA's typically run several times faster than the clock on legacy
hardware, and they may contain high level function blocks, e.g. multipliers
its often "relatively easy" to match the instruction times of a legacy CPU
in an FPGA. 

My BabyBaby FPGA implementation of the SSEM FPGA is such a beast. It runs at
the same speed as replica SSEM in MSI Manchester but internally it's a
parallel implementation whereas the real Baby is a serial machine.
https://hackaday.com/2016/01/06/babybaby-a-1948-computer-on-an-fpga/

5. Gate Level Hardware Emulation
It gate level hardware emulation we try and re-implement the hardware down
to the logic gate level. This is hard because FPGA's are may not be designed
to work this way, and gate level design will also have some dependencies on
propagation delays, which on an FPGA will be much smaller than on any real
hardware. A couple of examples of these are 

Laurence Wilkinson's IBM 360/30 http://www.ljw.me.uk/ibm360/
Carl Claunch's IBM 1130 http://ibm1130.blogspot.co.uk/

I hope this doesn't muddy the water too much...
Dave
  



> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Kip Koon
> via cctalk
> Sent: 27 October 2017 06:42
> To: 'Paul Koning' <paulkon...@comcast.net>; 'General Discussion: On-Topic
> and Off-Topic Posts' <cctalk@classiccmp.org>
> Subject: RE: Which Dec Emulation is the MOST useful and Versatile?
> 
> Hi Paul,
> Thank you for the info.  I tend to get emulation and simulation a bit
confused.
> Just so I understand simulation correctly, hardware emulation is when the
> functionality of the hardware is actually implemented in hardware somehow
> like VHDL in an FGPA and hardware simulation is when a program
> implements the functionality of the hardware in a software program no
> matter what hardware the hardware simulator is running on.  I think I got
this
> now.
> Correct?  Thanks a bunch for setting me straight.
> 
> 
> Kip Koon
> computer...@sc.rr.com
> http://www.cocopedia.com/wiki/index.php/User:Computerdoc
> 
> 
> -Original Message-
> From: Paul Koning [mailto:paulkon...@comcast.net]
> Sent: Thursday, October 26, 2017 4:29 PM
> To: Kip Koon; General Discussion: On-Topic and Off-Topic Posts
> Subject: Re: Which Dec Emulation is the MOST useful and Versatile?
> 
> 
> > On Oct 24, 2017, at 10:40 PM, Kip Koon via cctalk
<cctalk@classiccmp.org>
> wrote:
> >
> > ...
> > 2nd, a hardware emulator running a simulator written in 6809 assembly
> > language for the PDP-8/e running on a 6809 Core & I/O board system
> > seems like a good choice for me as I understand the 6809 microprocessor,
> ...
> 
> I would call that a software emulator; the fact that it runs on some
> microprocessor eval board doesn't make a difference

RE: Which Dec Emulation is the MOST useful and Versatile?

[Kip Koon via cctalk]

Hi Paul,
Thank you for the info.  I tend to get emulation and simulation a bit
confused.  Just so I understand simulation correctly, hardware emulation is
when the functionality of the hardware is actually implemented in hardware
somehow like VHDL in an FGPA and hardware simulation is when a program
implements the functionality of the hardware in a software program no matter
what hardware the hardware simulator is running on.  I think I got this now.
Correct?  Thanks a bunch for setting me straight.


Kip Koon
computer...@sc.rr.com
http://www.cocopedia.com/wiki/index.php/User:Computerdoc


-Original Message-
From: Paul Koning [mailto:paulkon...@comcast.net] 
Sent: Thursday, October 26, 2017 4:29 PM
To: Kip Koon; General Discussion: On-Topic and Off-Topic Posts
Subject: Re: Which Dec Emulation is the MOST useful and Versatile?


> On Oct 24, 2017, at 10:40 PM, Kip Koon via cctalk <cctalk@classiccmp.org>
wrote:
> 
> ...
> 2nd, a hardware emulator running a simulator written in 6809 assembly 
> language for the PDP-8/e running on a 6809 Core & I/O board system 
> seems like a good choice for me as I understand the 6809 microprocessor,
...

I would call that a software emulator; the fact that it runs on some
microprocessor eval board doesn't make a difference.  Running SIMH on a
Beaglebone would be analogous (though easier).

When you said "hardware emulator" I figured you meant an FPGA implementation
of a VHDL or Verilog model of the machine.  There are a bunch of those for a
variety of DEC computers.  One I have looked at is this one:
http://pdp2011.sytse.net/wordpress/ which incidentally is also configurable
to implement a choice of PDP11 model.

paul

Re: Which Dec Emulation is the MOST useful and Versatile?

[Paul Koning via cctalk]

> On Oct 24, 2017, at 10:40 PM, Kip Koon via cctalk  
> wrote:
> 
> ...
> 2nd, a hardware emulator running a simulator written in 6809 assembly
> language for the PDP-8/e running on a 6809 Core & I/O board system seems
> like a good choice for me as I understand the 6809 microprocessor, ...

I would call that a software emulator; the fact that it runs on some 
microprocessor eval board doesn't make a difference.  Running SIMH on a 
Beaglebone would be analogous (though easier).

When you said "hardware emulator" I figured you meant an FPGA implementation of 
a VHDL or Verilog model of the machine.  There are a bunch of those for a 
variety of DEC computers.  One I have looked at is this one: 
http://pdp2011.sytse.net/wordpress/ which incidentally is also configurable to 
implement a choice of PDP11 model.

paul

RE: SDS 940 BASIC (was Re: Which Dec Emulation is the MOST useful and Versatile?)

[Rich Alderson via cctalk]

From: Al Kossow
Sent: Thursday, October 26, 2017 9:04 AM

> On 10/25/17 11:55 AM, Rich Alderson via cctalk wrote:

>> Noel, do have a reference for "some commercial time-sharing system in the
>> Boston area"?  From Paul Allen's autobiography, the Harvard system was
>> followed immediately by their move to Albuquerque, where they leased time on
>> the local school board's PDP-10, and that's what my friends who worked for
>> Micro-soft back then have told me, as well.

> Harvard had an SDS 940, which shipped with a version of Berkeley's
> timesharing system. Tymshare's version of that system was significantly
> improved, and included "Super BASIC". SDS's OS was replaced with Tymshare's
> at Harvard because the original was so bad, and so they were exposed to that
> version of BASIC. PA told me that was the influence for M-S's BASIC
> extensions.

Harvard also had a KA-10, which is what PGA's 8008 -> 8080 simulator ran on,
using the User UUO capabilities of the architecture and operating system:
Microprocessor 8-bit byte in the address field, and a user-defined operation in
the opcode field to do the interpretation/call the interpreter.  (The simulator
was originally written for the Traf-O-Data device, which was 8008 based.)  I
put the code on our Tops-10 system while he was writing the book, and the
version of BASIC we run on the Altair 8800 in the Exhibit Hall was compiled on
that system; it is not a Microsoft product.

I know about the influence of SuperBASIC; I did not know about the Harvard 940.
Thanks for the note!

Rich


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computers: Museum + Labs
2245 1st Avenue S
Seattle, WA 98134

mailto:ri...@livingcomputers.org

http://www.LivingComputers.org/

Re: Which Dec Emulation is the MOST useful and Versatile?

[Al Kossow via cctalk]

On 10/24/17 7:40 PM, Kip Koon via cctalk wrote:

> The choice so far it seems is the PDP-11/70.  Remember I still have no idea
> beyond some searching on the internet what boards and peripherals a
> PDP-11/70 consists of.  For that matter, I don't know what boards and
> peripherals are in the PDP-8/e or PDP-8/I either.

bitsavers.org/pdf/dec has details for most of the DEC processors and software

Re: Which Dec Emulation is the MOST useful and Versatile?

[Noel Chiappa via cctalk]

> From: Kip Koon

> I was initially thinking of a strictly software only solution

Whatever you eventually do in the way of hardware, it might be a good idea to
start with this. You can get familiar with whatever OS you decide to go with,
and get used to its tools, get to know the instruction set of that
machine, etc, etc.

So then, if you do do a hardware project, it won't be such a big gulp, and
you'll have the knowledge base covering all the above already there to draw
on.


> which still presents a problem for me and that is which PDP do I teach
> myself and set up.

Probably the way to answer that is, if you're going to build hardware at some
point, a combination of 'what's out there that I can get to talk to', and
'how complicated a beast are we talking about'.

For the first, there's a lot of QBUS stuff around, some UNIBUS, and basically
zilch on the PDP-10 or PDP-15 front. For the second, most -11's (both QBUS
and UNIBUS) are relatively simple and straightforward. Any kind of PDP-10 is
pretty complex (depending on if you emulate the original busses, or not).

> 3rd, and this is a big factor in the choice of DEC PDP computer to pick
> for simulation or emulation and that is the small cash flow and itty
> bitty storage space I have available to me.

Noted.


> The choice so far it seems is the PDP-11/70.

If all you're doing is simulation (software), the -11/70 would be fine. It's
no more work to set up than one of the other timesharing-capable models; it's
only slightly more complicated than say, an -11/45, _from the programmer's
point of view_ (there's a UNIBUS map as well as the usual memory mapping
hardware), but if you're running an existing OS, that should not affect you.

> Remember I still have no idea ... what boards and peripherals
> a PDP-11/70 consists of.

Hardware-wise, the -11/70 could be a complex project - it depends on exactly
how much you try and emulate, a full emulation could be a very complex
undertaking indeed.

The thing is that while the /70 looks to the programmer a lot like one of the
simpler models, the hardware is quite a lot more complicated: there is a
cache, a separate memory bus, high-speed I/I controllers with their own
special bus to the devices (MASSBUS), etc. It's basically an -11/45 with a
bunch of extra stuff glued onto the sides of it to boost the performance; the
board count went from 10 (w/o floating point, which adds an extra 4) to a
minimum of of 16 (w/o FP), plus 4 for each high-speed I/O controller (up to
4).

Now, if all you're doing is emulating the system, _without_ providing any of
the busses, no problem; all that complexity is hidden inside the simulator.
But once you start emulating real busses (i.e. to be able to plug in real
hardware) - whole different kettle of fish.

Noel

SDS 940 BASIC (was Re: Which Dec Emulation is the MOST useful and Versatile?)

[Al Kossow via cctalk]

On 10/25/17 11:55 AM, Rich Alderson via cctalk wrote:

> Noel, do have a reference for "some commercial time-sharing system in the
> Boston area"?  From Paul Allen's autobiography, the Harvard system was 
> followed
> immediately by their move to Albuquerque, where they leased time on the local
> school board's PDP-10, and that's what my friends who worked for Micro-soft
> back then have told me, as well.

Harvard had an SDS 940, which shipped with a version of Berkeley's timesharing
system. Tymshare's version of that system was significantly improved, and 
included
"Super BASIC". SDS's OS was replaced with Tymshare's at Harvard because the 
original
was so bad, and so they were exposed to that version of BASIC. PA told me that 
was
the influence for M-S's BASIC extensions.

Re: Which Dec Emulation is the MOST useful and Versatile?

[Josh Dersch via cctalk]

On Wed, Oct 25, 2017 at 5:20 AM, william degnan via cctalk <
cctalk@classiccmp.org> wrote:

> On Tue, Oct 24, 2017 at 11:26 PM, Evan Koblentz via cctalk <
> cctalk@classiccmp.org> wrote:
>
> > Related to DEC emulation: is there a visual Straight-8 simulator? I'd
> like
> > to practice working the front panel and such.
> >
>
> I don't think there is one.  The PDP 8i is the closest thing but there are
> I think 26 switches at the bottom the 8i, I think only 18 at the bottom of
> the straight 8.


Both the 8/i and the Straight-8 have the same number of switches (26).
Their function is identical.  The 8/i has a few additional lights, however.

- Josh



> They thus can't be the same exactly but it may be that the
> straight 8 is the same as the 8i, if you use only switches that appear on
> both systems (no step counter on the straight 8).  Dave G will know.
>
> b
>

RE: Which Dec Emulation is the MOST useful and Versatile?

[Rich Alderson via cctalk]

From: Noel Chiappa
Sent: Tuesday, October 24, 2017 11:12 AM

>> From: Kip Koon

>> Back in the day when Bill Gates and company 1st started out ... a B/W photo
>> of a young Bill Gates bending over the operator at what looked like a very
>> small computer. Maybe it was just a terminal. I don't remember. I understand
>> they did software development on a DEC PDP of some sort.

> The very earliest version of their BASIC was done on PDP-10's running TOPS-10
> - first the one at Harvard, and then some commercial time-sharing system in
> the Boston area.

Noel, do have a reference for "some commercial time-sharing system in the
Boston area"?  From Paul Allen's autobiography, the Harvard system was followed
immediately by their move to Albuquerque, where they leased time on the local
school board's PDP-10, and that's what my friends who worked for Micro-soft
back then have told me, as well.

Rich


Rich Alderson
Vintage Computing Sr. Systems Engineer
Living Computers: Museum + Labs
2245 1st Avenue S
Seattle, WA 98134

mailto:ri...@livingcomputers.org

http://www.LivingComputers.org/

Re: Which Dec Emulation is the MOST useful and Versatile?

[william degnan via cctalk]

On Tue, Oct 24, 2017 at 11:26 PM, Evan Koblentz via cctalk <
cctalk@classiccmp.org> wrote:

> Related to DEC emulation: is there a visual Straight-8 simulator? I'd like
> to practice working the front panel and such.
>

I don't think there is one.  The PDP 8i is the closest thing but there are
I think 26 switches at the bottom the 8i, I think only 18 at the bottom of
the straight 8.  They thus can't be the same exactly but it may be that the
straight 8 is the same as the 8i, if you use only switches that appear on
both systems (no step counter on the straight 8).  Dave G will know.

b

RE: Which Dec Emulation is the MOST useful and Versatile?

[Kip Koon via cctalk]

Hi Guys,
I think I know so little of the PDP systems that I really didn't know how to
correctly phrase the question in PDP speak in my 1st email so let me try.
I was initially thinking of a strictly software only solution running on my
Windows 7 x64 laptop only since the only hardware based simulator I have is
the PiDP-8/I which is not up and running yet.  
I'm primarily a Motorola Processor man so after sending that 1st email I
found a gentleman's web site who built a PDP-11 Console front panel using a
6802 on the core board at 1st then redesigned the core board to use the 6809
and an I/O board working together as the controller for the PDP-11 front
panel.  The core board's serial port is connected to a PC running SimH
modified to communicate needed data to the front panel controller.  The url
link to his web site is below.
< http://www.pdp-11.nl/>
Click on the "My Projects" link on the left to see a quick summary of all of
his homebrew projects of which this is only one.  Now back to the core
board.
Of course the 6809 can be replaced with the 6309 as well.  Well, that really
sparked my interest as I am in the middle of designing a Motorola
Multi-Processor based single board computer board.  It will have the ability
to support all of the following processors however ONLY 1 CPU can be
populated on the PCB at a time as ALL address, data and control busses are
tied together using one common flash/eprom, ram, 2 serial ports and 4 -
8-bit parallel ports with 2 special control bits on each port.  The
processors that will be supported are the 6802, 6809, 6309 and the following
68HC11 sub-variants A1, A8, E2, F1 & K1.
So now my software only DEC Emulation idea is splitting into 2 thought
processes.
1st, a software simulator only way yields all currently supported PDPs which
still presents a problem for me and that is which PDP do I teach myself and
set up.  So far, it seems that you guys are saying that the PDP-11/70 is a
good choice whether SimH or Erzata-11 is used.  
A while back I found the PDP-8/e WinEight software simulator as one choice
as well.  SIMH can run them all. Still though, which one?
2nd, a hardware emulator running a simulator written in 6809 assembly
language for the PDP-8/e running on a 6809 Core & I/O board system seems
like a good choice for me as I understand the 6809 microprocessor, the 6821
Peripheral Interface Adapter and the 6850 Asynchronous Communications
Interface Adapter chips used on the core board reasonably well.  
There is a PDP-11 version of this hardware emulator available with only 1
more requirement and that is SIMH is running on a PC which communicates via
serial port the data needed to control the PDP-11 front panel.
3rd, and this is a big factor in the choice of DEC PDP computer to pick for
simulation or emulation and that is the small cash flow and itty bitty
storage space I have available to me.
So with what I have to work with, my current interests and skill level of
PCB design using the Motorola 8-bit processors as well as using Windows 7
x64 for software only simulations, which PDP should I chose?  
The choice so far it seems is the PDP-11/70.  Remember I still have no idea
beyond some searching on the internet what boards and peripherals a
PDP-11/70 consists of.  For that matter, I don't know what boards and
peripherals are in the PDP-8/e or PDP-8/I either.
I hope this helps you all understand me and my desires a little better.
Please keep your ideas, suggestions and questions coming.  You have my
complete attention!  I'm sitting on the edge of my seat as it were.  :)  I'm
beginning to see that this is going to be a very long term project.  Cool!
I need something to keep my mind sharp.  Take care my friends.

Kip Koon
computer...@sc.rr.com
http://www.cocopedia.com/wiki/index.php/User:Computerdoc


-Original Message-
From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Kip Koon
via cctalk
Sent: Tuesday, October 24, 2017 1:44 AM
To: 'General Discussion: On-Topic and Off-Topic Posts'
Subject: Which Dec Emulation is the MOST useful and Versatile?

Hi DEC Enthusiast's,

If I were to have to decide on just one model DEC PDP system to run in a DEC
Emulator, which one would be the most useful, versatile and has the most
software available for it?

I have only ever used a real PDP-8/e system way back in high school so I'm
not up to par on any other model of DEC PDP system and I only know BASIC on
the PDP-8/e so not much there either.

I hear a lot about the PDP-11.  I found out that there were 16 major PDP
models at one time so I'm not too sure which one to pick.  

I built Oscar Vermeulen's PiDP-8/I which I'm waiting on 1 part for.  Other
than that project which is in a holding pattern at the moment, I have no
other PDP anything running in any form.

Back in the day when Bill Gates and company 1st started out, I had always
wondered how they developed their very 1st software program - Altair Basic.
I was pleasantly surprised one day when I saw a B/W 

Re: Which Dec Emulation is the MOST useful and Versatile?

[Noel Chiappa via cctalk]

> From: Kip Koon

> f I were to have to decide on just one model DEC PDP system to run in a
> DEC Emulator, which one would be the most useful, versatile and has the
> most software available for it?

To echo what others have said, when you say 'emulator', do you mean hardware
(the usual meaning of emulator), or software (which would be a simulator)?
And if you mean hardware, are you going to emulate the bus as well?

Having said that, I think you should ask yourself 'what do you want to do
with it'? The thing is there are a lot of DEC machines which are
'interesting', and have a lot of software available for them: the -8, -10,
11, -15 and VAX (dunno if you consider that a 'PDP') are all in that category.

> I hear a lot about the PDP-11. I found out that there were 16 major PDP
> models at one time so I'm not too sure which one to pick.

They aren't really that different; many of them are more 'the optimal
technology to implement in' changed over the (fairly) long life of the
architecture, so many of models are where an earlier one was replaced by a
more cost-effective equivalent. E.g.  for one 'class', the /20 (TTL SSI) was
followed by the /05 (microcoded TTL SSI), and then the /04 (TTL MSI), and then
the /03 (LSI); in another the /40 was followed by the /34 and then the
/23. Etc. There are really only 3 kinds of -11:

- Those without memory management (the /20, etc)
- Those with 'simple' memory management (the /40, etc)
- Those with 'complex' memory management (all the others)

Simple software will run on all three; more complex (e.g. Unix) only on the
latter two.

> Back in the day when Bill Gates and company 1st started out
> ... a B/W photo of a young Bill Gates bending over the operator at what
> looked like a very small computer. Maybe it was just a terminal. I
> don't remember. I understand they did software development on a DEC PDP
> of some sort. 

The very earliest version of their BASIC was done on PDP-10's running TOPS-10
- first the one at Harvard, and then some commercial time-sharing system in
the Boston area.

> I have many projects in the works already so I decided to setup a
> software emulation of just one of the DEC PDP models.

OK, so it's going to be just running a simulator?

> I have heard a lot about the PDP-11 which if the information I read is
> correct was 16-bits. in the world... The PDP-11 is the model I hear the
> most about. 

Well, for good reason, I think.

It was at one point (1980), the best-selling computer, and really made the
minicomputer (yes, I know the -8 was the first successful mini, but their
size/computing power range was a lot smaller than the -11, and so it didn't
have as widespread a utilization as with the -11).

It's also the machine that Unix was developed on, so if you want to play
around with the 'classic' early Unixes (e.g. Version 6), you'll be wanting
to go with the -11.

Finally, it is to me the finest architecture ever, in terms of elegance, and
bang/buck - the power they squeezed into a 16-bit instruction is pretty
mind-blowing. If you want to see a really elegant design, look at the -11. A
lot of later architectures stole a lot of ideas from the -11.

If you want to go the -11/V6 route, there are instructions for doing
so here:

  http://gunkies.org/wiki/Running_Unix_v6_in_SIMH
  http://gunkies.org/wiki/Installing_UNIX_Sixth_Edition_on_Ersatz-11

and I have a very detailed page for doing so with the Ersatz-11 simulator
(which is _very_ fast, and easy to work with), with a lot of useful pre-built
disks, and tools, here:

  http://www.chiappa.net/~jnc/tech/V6Unix.html


The other one I would point to as 'interesting' is the PDP-10, _especially_
if you run ITS on it. There's a very complete and detailed page here:

  https://www.cosmic.com/u/mirian/its/itsbuild.html

for bringing it up under SIMH. There's also KLH10 as a simulator, which I
know a lot of people like for running ITS; instructions here:

  http://its.victor.se/wiki/setup

which has a lot of detail about how to get things running _on_ your ITS once
you have it up.


Please let us know what you decide... :-)

Noel

RE: Which Dec Emulation is the MOST useful and Versatile?

[Rob Jarratt via cctalk]

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Dave Wade
> via cctalk
> Sent: 24 October 2017 10:01
> To: 'Kip Koon' <computer...@sc.rr.com>; 'General Discussion: On-Topic and
> Off-Topic Posts' <cctalk@classiccmp.org>
> Subject: RE: Which Dec Emulation is the MOST useful and Versatile?
> 
> Kip,
>  It depends on what your interest is! Of course PDP stood for "Programmed
> Data Processor"
> 
> https://en.wikipedia.org/wiki/Programmed_Data_Processor
> 
> and avoids the use of the word computer because the backers of Digital did
not
> want them building a Computer. I believed it also helped sales as it
by-passed
> corporate purchasing edicts which said only central IT departments could
buy
> computers...
> 
> The PDP8 is the smallest but most hackable, but things like Oscars 8I or
the
> SBC6120 which turns up from time to time (google SBC6120) mean that its
> possible to have something approaching a physical PDP-8 to play with
rather
> than just emulation. But if small is beautiful then may be the machine for
you.
> These were used all over the place. Manchester University Medical School
had
> one connected to its IBM7090, Leeds to its KDF9. Really a revolution in
> computing. Its amazing what folks got to run on these using only paper
tape.
> Eventually made in a Microprocessor with the Harris and Interrail 6100 and
> then the Harris HD6120..
> 
>  The PDP-11 covers a huge range of systems and I know there are still some
> PDP-11's in service. At one time Barclays, a UK bank used them as Branch
> Controllers so every branch had a PDP-11 and in those days there were many
> more branches than there are now. I learnt BASIC on one at Salford
University
> in 1977. When I worked for the uk's Natural Environment Research Council
we
> must have had hundreds of the things. We used them to build "media
> conversion" systems that would copy data from scientific instruments and
to
> build front end concentrators for our Honeywell L66. More capable than the
> PDP-11 but possibly less easy to hack. Lots of different Operating Systems
out
> there but for some licensing is interesting.  Was used to develop early
Unix
> 
>  The VAX-11 is probably my favourite box. I have several physical VAXen
all
> with the VMS OS installed. Really gives a flavour of what interactive
computing
> was like in the 1970's and 1980's. Very capable but even less easy to
hack, and
> initially big and expensive, which is why the PDP-11 continued to be
available
> for many years.
> 
>  There is also the PDP-10/Dec System 10 which was claimed to be a
Mainframe
> but I never met one of these. Probably not for the faint hearted.
> 

Ah the PDP10! Although the very first computer I used was a PDP11, it was so
briefly that I really consider the PDP10 (in DECSYSTEM-20 form) to be my
first computer. It is easy to emulate in SIMH, although the SIMH emulation
is of a less capable processor (KS10) and I think KLH10 is the best emulator
for that (but I have never used it).

For general DEC goodness I would go for a PDP11 or a VAX, preferably both.
And as Dave and others have pointed out, PDP was not really a line of
computers, it was multiple lines of different computers.

I forsee a *long* thread here.

Regards

Rob

Re: Which Dec Emulation is the MOST useful and Versatile?

[allison via cctalk]

On Oct 24, 2017, at 1:44 AM, Kip Koon via cctalk  wrote:

Hi DEC Enthusiast's,

If I were to have to decide on just one model DEC PDP system to run in a DEC
Emulator, which one would be the most useful, versatile and has the most
software available for it?

I have only ever used a real PDP-8/e system way back in high school so I'm
not up to par on any other model of DEC PDP system and I only know BASIC on
the PDP-8/e so not much there either.

I hear a lot about the PDP-11.  I found out that there were 16 major PDP
models at one time so I'm not too sure which one to pick.

I built Oscar Vermeulen's PiDP-8/I which I'm waiting on 1 part for.  Other
than that project which is in a holding pattern at the moment, I have no
other PDP anything running in any form.



The problem is how your asking.

First question is there is not one PDP system  and more than there is 
one FORD.

So you have to narrow the question to your interests such as 12, 16, 18, 32,
 or 36 bit systems as DEC made many very different systems.

Of those the PDP-8 series, 12 bit are interesting.
PDP11 the 16bit line
or for the unusual 18 bit PDP-7 or 36 bit PDP10.
There is even emulation for PDP-1 (18bit).

When you ask what is more versatile are you asking about the emulator or
the emulated end system?

For most the PDP-8 as its one system where the hardware and software is 
fairly

understandable to the lowest levels.

For the PDP-11 the variety of hardware and system configurations are 
nearly exceeded
by operating system and user software.  Its also the definitive Unix 
machine to some.

Its is one of my favorites either 11/73 as hardware or 11/70 as a sim.

As to SIMs  SIMH is by far the most widely known and versatile, with it 
and software

you can emulate most anything even something from your imagination.

E-11 Aka Ersatz-11 is a very good PDP-11 emulator.

There are no shortage of other simulators.  I'm sure everyone has their 
favorites.


Me I'm into the actual hardware so I have PDP-8F, an assortment of 
PDP11s from
the initial LSI-11 though the 11/73 hardware.  That and a boat load of 
MicroVAX
systems.  I limit my DEC systems to that scope for space mostly. THe 
rest of the

hardware in the collection is CP/M based (S100, Kaypro, Ampro...).

So pick a DEC system that has interest and simulate it or all if you 
have time.


Allison

Re: Which Dec Emulation is the MOST useful and Versatile?

[william degnan via cctalk]

On Tue, Oct 24, 2017 at 8:06 AM, Paul Koning via cctalk <
cctalk@classiccmp.org> wrote:

>
> > On Oct 24, 2017, at 1:44 AM, Kip Koon via cctalk 
> wrote:
> >
> > Hi DEC Enthusiast's,
> >
> > If I were to have to decide on just one model DEC PDP system to run in a
> DEC
> > Emulator, which one would be the most useful, versatile and has the most
> > software available for it?
> >
>

I think OS/8 is pretty good for a one user system, if that's what you're
using it for.  You already kind of know it and one can run a lot of
languages on it.  I'd agree about the 11/70, but only if you're running the
kinds of applications found on the disk images that are out there.
Otherwise over time you can make your own tapes/RL02/RK05.etc disk pack
sets (or whatever) to emulate in.

I have a Next Thing CHIP with as many SimH builds and images as I could
find and test to set up, DEC included, so I can switch around at will.  I
have my a serial terminal for I/O.  Certainly never get bored with that
kind of setup.

Bill

Re: Which Dec Emulation is the MOST useful and Versatile?

[Paul Koning via cctalk]

> On Oct 24, 2017, at 1:44 AM, Kip Koon via cctalk  
> wrote:
> 
> Hi DEC Enthusiast's,
> 
> If I were to have to decide on just one model DEC PDP system to run in a DEC
> Emulator, which one would be the most useful, versatile and has the most
> software available for it?
> 
> I have only ever used a real PDP-8/e system way back in high school so I'm
> not up to par on any other model of DEC PDP system and I only know BASIC on
> the PDP-8/e so not much there either.
> 
> I hear a lot about the PDP-11.  I found out that there were 16 major PDP
> models at one time so I'm not too sure which one to pick.  
> 
> I built Oscar Vermeulen's PiDP-8/I which I'm waiting on 1 part for.  Other
> than that project which is in a holding pattern at the moment, I have no
> other PDP anything running in any form.

When you say "emulation" do you mean a software emulator like SIMH or E11?  For 
those, the model choice is just a startup parameter, so you can change at will.

Or do you mean an FPGA based one like PDP2011?  There too the choice is a 
parameter, when you build the VHDL into the actual FPGA bits.

In any case, if you want to pick a particular model, I would say 11/70 is a 
good choice.  While near the end of the PDP11 era the Q-bus became mainstream, 
for much of the time the Unibus was either the only or at least the primary I/O 
bus.  It has the full memory management unit and full floating point, so any 
software that requires these is happy.  It has 22 bit addressing for big 
memory.  And it is old enough that early operating systems like DOS will work.  
You could even turn on CIS instructions and call it an 11/74, the semi-mythical 
11/70 variant for commercial applications (COBOL) that never shipped, some say 
because it was too good compared to the VAX 11/780.

One more consideration: if by "emulator" you mean something in hardware that 
has an actual DEC I/O bus coming out of it and accepts real DEC cards, then a 
Q-bus system may be better, it depends on what I/O devices you can most readily 
find.  If so, I'd go for the 11/73.

paul

RE: Which Dec Emulation is the MOST useful and Versatile?

[Dave Wade via cctalk]

Kip,
 It depends on what your interest is! Of course PDP stood for "Programmed
Data Processor"  

https://en.wikipedia.org/wiki/Programmed_Data_Processor

and avoids the use of the word computer because the backers of Digital did
not want them building a Computer. I believed it also helped sales as it
by-passed corporate purchasing edicts which said only central IT departments
could buy computers...

The PDP8 is the smallest but most hackable, but things like Oscars 8I or the
SBC6120 which turns up from time to time (google SBC6120) mean that its
possible to have something approaching a physical PDP-8 to play with rather
than just emulation. But if small is beautiful then may be the machine for
you. These were used all over the place. Manchester University Medical
School had one connected to its IBM7090, Leeds to its KDF9. Really a
revolution in computing. Its amazing what folks got to run on these using
only paper tape. Eventually made in a Microprocessor with the Harris and
Interrail 6100 and then the Harris HD6120..

 The PDP-11 covers a huge range of systems and I know there are still some
PDP-11's in service. At one time Barclays, a UK bank used them as Branch
Controllers so every branch had a PDP-11 and in those days there were many
more branches than there are now. I learnt BASIC on one at Salford
University in 1977. When I worked for the uk's Natural Environment Research
Council we must have had hundreds of the things. We used them to build
"media conversion" systems that would copy data from scientific instruments
and to build front end concentrators for our Honeywell L66. More capable
than the PDP-11 but possibly less easy to hack. Lots of different Operating
Systems out there but for some licensing is interesting.  Was used to
develop early Unix

 The VAX-11 is probably my favourite box. I have several physical VAXen all
with the VMS OS installed. Really gives a flavour of what interactive
computing was like in the 1970's and 1980's. Very capable but even less easy
to hack, and initially big and expensive, which is why the PDP-11 continued
to be available for many years.

 There is also the PDP-10/Dec System 10 which was claimed to be a Mainframe
but I never met one of these. Probably not for the faint hearted.

Dave

> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Kip Koon
> via cctalk
> Sent: 24 October 2017 06:46
> To: cctech 
> Subject: Which Dec Emulation is the MOST useful and Versatile?
> 
> Hi DEC Enthusiast's,
> 
> If I were to have to decide on just one model DEC PDP system to run in a
DEC
> Emulator, which one would be the most useful, versatile and has the most
> software available for it?
> 
> I have only ever used a real PDP-8/e system way back in high school so I'm
> not up to par on any other model of DEC PDP system and I only know BASIC
> on the PDP-8/e so not much there either.
> 
> I hear a lot about the PDP-11.  I found out that there were 16 major PDP
> models at one time so I'm not too sure which one to pick.
> 
> I built Oscar Vermeulen's PiDP-8/I which I'm waiting on 1 part for.  Other
than
> that project which is in a holding pattern at the moment, I have no other
PDP
> anything running in any form.
> 
> Back in the day when Bill Gates and company 1st started out, I had always
> wondered how they developed their very 1st software program - Altair
Basic.
> I was pleasantly surprised one day when I saw a B/W photo of a young Bill
> Gates bending over the operator at what looked like a very small computer.
> Maybe it was just a terminal.  I don't remember.  I understand they did
> software development on a DEC PDP of some sort.
> 
> Finding this out regenerated my interest in the DEC PDP line of computers.
> 
> I have many projects in the works already so I decided to setup a software
> emulation of just one of the DEC PDP models.  I have heard a lot about the
> PDP-11 which if the information I read is correct was 16-bits.  My
PiDP-8/I is
> 12 bits.  I understand the PDP 10 was 36-bits and the PDP-15 was 18-bit.
> The PDP-11 is the model I hear the most about.
> 
> I also have some experience on some version of  a VAX when I was in the
Air
> Force so I'm thinking of getting a VAX emulation going at some point too.
> 
> So if I'm going to do this, what suggestions, pointers, experiences,
etcetera
> do you guys have for me.  I am very interested in the DEC PDP equipment
> though next to no experience so I have no basis to make a decision.  This
is a
> serious request so I would definitely like to hear what you all have to
say.  If
> you have read this far, thank you.  Take care my friends.
> 
> 
> 
> 
> 
> Kip Koon
> 
> computer...@sc.rr.com
> 
> http://www.cocopedia.com/wiki/index.php/User:Computerdoc
> 
>