Re: CESI VM8128 PDP8-A 128 K MOS?

[Doug Ingraham via cctalk]

As stated this is a 128k word mos memory board for the 8/a processor.  On
its own it would only present as a 32k board.  To make it work as a 128k
you also need to have a M8416 board which drives the additional address
lines.  And not all 8/a chassis had support for this.  All 4 of my
backplanes have a label indicating KT8A support.  I am guessing that
originally the additional address lines were not connected across the
backplane on the 6th connector.  My card does have some bad bits and one of
these days I will get around to replacing some chips.  This is probably why
I was able to get it not paired with the fancy MMU card.

I have an M8417 but have been unable to find an M8416 at a price I was
willing to pay.  Apparently there are still a few 8/a's with these cards in
service in Genrad testers and that makes the cards still valuable.

There is info on it in the PDP 8/a PDF's on bitsavers.  I think there was a
TSS8 variant that used it as a fast swap but I don't know of anything else
from DEC that supported it.

Best Wishes!



On Fri, Aug 24, 2018 at 5:38 AM, allison via cctalk 
wrote:

> On 08/24/2018 07:06 AM, Rod G8DGR via cctalk wrote:
> > M8417 MSC8DJ PDP8A 128K MOS
> >
> > Clone of this
> >
> >
> >
> > Sent from Mail for Windows 10
> >
> > From: Paul Anderson via cctalk
> > Sent: 24 August 2018 10:12
> > To: General Discussion: On-Topic and Off-Topic Posts; cct...@vax-11.org
> > Subject: CESI VM8128 PDP8-A 128 K MOS?
> >
> > I have an idea what this might be, but I can't find anything to confirm
> it
> > on line. Can anyone shine some light on it?
> >
> > Thanks, Paul
> >
> its a 128 memory card If memory is right hex width for PDP-8A... The
> last of the omnibus 8s.
> That machine had extended the MMU used in earlier PDP-8 from 3 EMA lines
> to 5.
> Only fits the 8A chassis.
>
> Allison
>



-- 
Doug Ingraham
PDP-8 SN 1175
Assorted 8/a chassis
DECSet 8000 (It is a blue PDP 8/e okay?)

Re: PDP8/e programmers consoles

[Doug Ingraham via cctalk]

On Wed, Mar 21, 2018 at 8:04 PM, Charles Dickman <c...@chdickman.com> wrote:

> On Tue, Mar 20, 2018 at 11:27 AM, Doug Ingraham via cctalk
> > I guess you can be the first!  Best wishes.
>
> Not sure I want to go there...
>

I hear you there.  I built a front panel for a box I have been calling the
FPG-8.  Modeled after the Straight 8 front panel.  I probably have 100
hours into it at the point I stalled out.  Next step is silk screening the
glass face plate.  Electrically the panel works.  Can do a walking 1's
of the LED's  Can sense all the switches.  Now that I have a 3D
printer I am thinking about a redo of the switches.  They are just
toggle switches right now.  If I tilt them down so when on the handle
sticks straight out (~20 degrees) and add a plastic handle cover
resembling the DEC ones it will look really close.

So expect a few hundred man hours in making a PCB front panel for
omnibus with all the bells and whistles.  Sometimes the things that seem
easiest turn out to be difficult.


> If you have ever looked at the DEC part number listing on bitsaver's
> you will be amazed at all the specials that were done. And that was
> what I was really interested in. Did DEC ever make a fancy panel that
> displayed all the registers? The original designer had it in mind
> since he displays a selected register at runtime during TS1 and when
> the processor is stopped since that is TS1.


As far as I know there are only 3 front panel variants made for omnibus.

1) lamp 8/e panel. (found on e f m lab-8 and DECSet 8000)
2) LED 8/e panel.  (almost the same as 1)  (Found on e, f, m, probably
Lab-8 and possibly on DECSet 8000.)
3) 7 segment LED panel with keypad on 8/a.  (Still only shows one at
 a time.)

Minor variants of these but none that display all registers/states at the
same time.  Yes you could do this but the panel size would probably
have to increase.  I am sure part of the reason they did it the way they
did was to cut costs.  More lamps would have added considerably to
the cost.  And very little additional gain to functionally.  Most of the
"specials" were probably just different screens on front panels with the
underlying hardware unchanged.  That is certainly true of the Lab-8 and
DECSet 8k.

Best wishes!

-- 
Doug Ingraham
PDP-8 SN 1175

Re: PDP8/e programmers consoles

[Doug Ingraham via cctalk]

On Mon, Mar 19, 2018 at 8:02 PM, Charles Dickman via cctalk <
cctalk@classiccmp.org> wrote:

> On Fri, Mar 16, 2018 at 9:59 PM, allison via cctalk
>  wrote:
>
> >> Has anyone ever seen a PDP8/i style console for the PDP8/e? Looking at
> >> the way the PDP8/e console functions, it should be possible to time
> >> multiplex all the register to the data bus so they are all visible at
> >> once when the machine is halted.
> > No and can't!   The 8i (nor the 8L) was not omnibus.  The boards to make
>
> I know the 8/I panel won't work with an 8/e. My question was if there
> was a special seen in the wild that had all the register values like
> the 8/i did since the panel interface clearly supports it.
>

This would certainly be possible.  I discussed exactly this possibility a
few years
ago with a now departed friend.  We did a cursory search at the time and
didn't
turn up anything.  Of course there are lots of smart people out there who
do a lot
of clever things and never bother to tell the net.  My bet would be that
nobody
has wanted this enough to make their own omnibus front panel when there are
still real panels and machines readily available.

I guess you can be the first!  Best wishes.

-- 
Doug Ingraham
PDP-8 SN 1175

Re: PDP8/e programmers consoles

[Doug Ingraham via cctalk]

The circuit board material of the straight 8 front panel is fragile.  The
resin
used melts at soldering temperatures.  As a consequence my front panel
was munged up before I got it.  Foils lifted kind of thing.  I decided when
I
next took it apart I would replace with LED's.  Around 1995 I had some
super bright white LED's and I worked out an appropriate current limiting
resister value and replaced three bulbs with LEDs.  They work but the
color temp was far too blue.  Also they activate at far too low of current
and will trigger from cross talk in the wiring when the cpu is running.
They also turn on and off too quickly.  The thermal inertia of a filament is
missing.

If you were a bit crazy you could use a CPU with an 8 bit A/D and drive a
color LED to accurately emulate a bulb.  Simpler is something like this.

  Bulb lead
|
++---+
  +---+  \   |
  |LED|  /  ---
  +---+  \  ---
|/   |
++---+
\
/
\
/
  -
   ---
-

Parts list is LED, two resistors, and a cap.  The resistor on the bottom is
to limit the brightness.  The resistor in parallel with the LED is to
control
the LAMP off brightness and cross talk illumination.  The cap is used to
slow down the on/off time and make it look more like it has some thermal
mass.

The minimum needed to make this work is the LED and the series resistor.
With modern super bright LEDs I would sand off the dome making a flat
face which diffuses the output making it unfocused.  I am also betting
that 1 ma will be too bright but lets shoot for that.  In the case of the
8/e
with an 8 volt lamp driver (assumption) if you want 1 ma of current and
the LED is ~3 volts for the white ones.  (8 volts - 3 volts)/0.001 amps
gives
a resistance of 5000 ohms.  I have seen white LEDs with a voltage of 2.7
and up to 3.2 and this gives a range of 4.8 k to 5.3 k for a 1 ma current.

Depending on what you get for LED's will determine the value of the
resistors needed.

My 8/e variant is a DECSet 8000 and the front panel has a red filter so it
would look pretty much the same with lamps or period correct red LEDs.

Best Wishes!

-- 
Doug Ingraham
PDP-8 SN 1175

Re: Bug-for-bug compatibility [was RE: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]]

[Doug Ingraham via cctalk]

On Tue, Feb 27, 2018 at 2:46 PM, Rich Alderson via cctalk <
cctalk@classiccmp.org> wrote:
>
> Fast forward 20 years, to Living Computer Museum, where a KI-10 based
> DEC-1070
> was undergoing restoration.  Diagnostics were needed, so the resident
> TOPS-20
> programmer laid hands on the MAINDEC sources for the KI-10 and proceeded to
> compile them all and generate paper tapes of the results.  All went
> smashingly
> well until the multiplication test.
>
> The diagnostic source for this test uses a macro to build a set of test
> values
> for X**2 where X is a power of 2.  Internally, Macro-20 uses the IMULM
> instruction to build the results.  In the KA-10 manual, IMULx of 2**35 *
> 2**35
> is supposed to store the high order part of the result into the 36 bit word
> addressed by the instruction, and set the overflow bit.
>
> On the Toad-1 (and on the Toad-2 prior to our discovery of this bug), a
> zero is
> stored instead.  Since we compiled the KI-10 diagnostics on the Toad-1,
> this
> incorrect result was placed on the diagnostic paper tape, and the KI-10
> seemed
> to fail the diagnostic.  Imagine our chagrin when days of trying to
> correct the
> problem led to the conclusion that the diagnostic was incorrect.
>
> Rich
>

This is a great story!  And it probably indicates that when developing the
Toad-1 this particular
diagnostic was never run from an original DEC generated tape or the Toad-1
would have failed
the diagnostic.  Alternatively assembling the diag on the restoration
project would have yielded
a working multiply.

So is someone going to fix the multiply instruction in the 20+ year old
Toad? 

-- 
Doug Ingraham
PDP-8 SN 1175

Re: SimH DECtape vs. Tops-10 [was RE: Writing emulators [Was: Re: VCF PNW 2018: Pictures!]]

[Doug Ingraham via cctalk]

On Fri, Feb 23, 2018 at 2:49 PM, Rick Murphy via cctalk <
cctalk@classiccmp.org> wrote:

> On 2/21/2018 5:14 PM, Paul Koning via cctalk wrote:
>
>> Ok, then it could be for VMS, which also does this (via Andy's
>> unsupported driver).  I don't know of PDP-11 or other minicomputer systems
>> that do DECtape overlapped seek.  I suppose it could be for artistic
>> verisimilitude...
>>
>
> TSS/8. It was a wonderful thing to witness. Start the drive spinning,
> deselect it, go start up another, then reselect the first one as it
> approached the right part of the tape.
> -Rick
>

The purpose of an emulator is to accurately pretend to be the original
hardware.  It doesn't matter that the original OS runs on a particular
emulator.  If a program can be written that runs on the original hardware
but fails on the emulator then there is a flaw in that emulator.

I've been slowly working on a PDP-8 emulator since the mid 1980's.  It was
able to run code a couple of days after I started working on it.  FOCAL in
about a week.  The Teletype emulation timing was added early on so a
program could not tell it was running on the emulator by timing the TTY
instructions.  About 10 years ago I added acceleration curves to the high
speed paper tape reader timing.  Within the last year I have added DF-32
support and am working towards fixing the timing so a program could not
be written to tell.  I need to add a randomness factor to the inter platter
timing.  At the moment it looks like all the drives are in optimum lockstep
which makes transfers run a little faster but isn't reality.  Probably add
a 50 hz option for those in 50 hz countries since the drive motors run
slower there and thus transfers were slower.

I have delayed adding DECTape support for years because of the difficulty
of doing this correctly.  You need to support so much stuff to do this
right from a timing standpoint.  At least on the TC01 controller you can
read in the reverse direction as well as the normal forward direction.  Do
you need to support reverse reads?  Almost no software took advantage of
this.  Every drive runs a little different and the emulator could (should)
reflect this.

If you can't have a real machine the least you can have is a correct as
possible emulator.  It is a lot easier to be lazy and think you are done
when the OS boots or an interpreter appears to run or it passes
diagnostics.  In reality you have barely begun.


-- 
Doug Ingraham
PDP-8 SN 1175

Re: DECtape madness

[Doug Ingraham via cctalk]

On Sat, Jan 13, 2018 at 7:34 AM, David Bridgham via cctalk <
cctalk@classiccmp.org> wrote:

> I've wondered if you might not make DECtape tape from 3/4" video tape.
> I know that DECtape has mylar on both sides but what if you somehow
> glued two strips of video tape together with the mylar backing on the
> outside.  Probably want to build a jig of some sort and I'm not sure
> what glue to use.
>

I have read on several occasions about the mylar on both faces of the
tape.  I have over 300 reels of DECTape in my collection.  Most of these
are 3M Scotch branded but around 30 of them are DEC branded in the blue
plastic boxes.  I have never seen one with mylar on both sides.  This may
have been something that existed early on but certainly wasn't the norm.



-- 
Doug Ingraham
PDP-8 SN 1175

Re: Did DEC make a Daisy Wheel printer?

[Doug Ingraham via cctalk]

On Tue, Oct 10, 2017 at 1:50 PM, Electronics Plus via cctalk <
cctalk@classiccmp.org> wrote:

> I had some DEC branded daisy wheel printers years ago, but they are long
> gone now. There was also an LA75 and and LA210, IIRC.
>
> Cindy
>
> -Original Message-
> From: cctalk [mailto:cctalk-boun...@classiccmp.org] On Behalf Of Jon
> Elson via cctalk
> Sent: Tuesday, October 10, 2017 11:02 AM
> To: Adrian Graham; gene...@ezwind.net; discuss...@ezwind.net:On-Topic and
> Off-Topic Posts
> Subject: Re: Did DEC make a Daisy Wheel printer?
>
>
> >> On 10/08/2017 10:19 AM, Zane Healy via cctalk wrote:
>  Did DEC make any sort of impact printer, besides dot-matrix
> printers?  I have an LA50 or two, and dot-matrix isn’t what I’m after.
> >>>
> DEC sold a number of printers of varying speeds.  I think they may all
> have been drum printers, but there may have been a band or train printer,
> too.  these were all based on mechanisms made by other outfits, with DEC
> controller and branding.  But, not a lot of installations bought them, as
> DEC added a premium to the price. I've only seen the real DEC printers in
> advertising and handbook photos.
>
> jon
>
>
> ---
> This email has been checked for viruses by Avast antivirus software.
> https://www.avast.com/antivirus
>
>
I have a DEC branded daisy wheel printer.  I think it is a Diablo 1620.  It
was part of a ClassIC which is an 8/a with RX-01 and VT terminal of some
type in a desk with a chair.  This one had the daisy wheel printer and a
DECwriter.  I have not looked closely at the printer mechanism.  The
DECwriter is in pretty bad shape but I have the 8/a and RX-01 running
(mostly).  The original desk and chair are going to be refurbished next.

What is the purpose of the query?

-- 
Doug Ingraham
PDP-8 SN 1175

Re: Aaron Nabil & pdp-8.org

[Doug Ingraham via cctalk]

The whois record for pdp8.org lists its DNS servers as ns.spiritone.com and
ns2.spiritone.com.
What is interesting is that neither of those entries are in the
spiritone.com dns servers from my
point of view.  However DNSStuff can get A records for those queries.  This
means that they are
providing different views probably depending on if you are inside their
network or outside.   And
they probably let DNSStuff in because that makes stuff look less broken.
The simplest solution
is to host the record with the registrar or one of the professional hosting
services.  Usually the
registrar will host the record as part of the registration fee.





On Sun, Oct 8, 2017 at 2:25 PM, Zane Healy via cctalk  wrote:

>
> > On Oct 8, 2017, at 1:22 PM, Vincent Slyngstad via cctalk <
> cctalk@classiccmp.org> wrote:
> >
> > I wrote to Aaron a couple of days ago, and mentioned Jay's offer to him.
> >
> > I did hear back from him -- he's aware of the problem and does have his
> site backed up.
> > (He didn't volunteer any details about his plans, but I assume he's got
> things in hand.)
> >
> >   Vince
>
> Thanks Vince, I’ve not spoken to Aaron for years, so good to know he’s
> still around.
>
> Zane
>
>
>


-- 
Doug Ingraham
PDP-8 SN 1175

Re: Warren Stearns info.

[Doug Ingraham via cctalk]

On Fri, Aug 11, 2017 at 5:14 PM, Chuck Guzis via cctalk <
cctalk@classiccmp.org> wrote:

>
> Was Warren Stearns connected with Stearns Computer Systems, maker of the
> short-lived Stearns PC?
>
> --Chuck
>

No, he wasn't.



-- 
Doug Ingraham
PDP-8 SN 1175

Warren Stearns info.

[Doug Ingraham via cctalk]

Warren Stearns passed away early on Sunday August 6th.  He suffered a heart
attack on Friday the 4th and never recovered from that.  Warren was an avid
collector and maintainer of DEC PDP-8 equipment.  He and I met almost 43
years ago while in college and have kept in touch all this time because of
our similar interest in these machines.  Warren recently assisted in
bringing a PDP-12 back to life at the University of Minnesota in Duluth.
He has been working on a Flip Chip tester for a couple of years now and has
been using a bread boarded early version of this for several years.

I am hoping I can find someone with the knowledge and drive to continue
working on his tester as this is something that would greatly benefit those
of us who are trying to keep these machines alive.  I will try to collect
all the work he was doing on it together in one place for this purpose.  At
the moment I have his tester and his 8/a and 8/i projects.  His laptop is
with one of his brothers but I will get a copy of all his engineering and
data files.

-- 
Doug Ingraham
PDP-8 SN 1175

Re: pdp-8/e restoration.

[Doug Ingraham via cctalk]

On Fri, Aug 4, 2017 at 1:24 AM, Rod Smallwood via cctalk <
cctalk@classiccmp.org> wrote:

> 1. Should the run light glow dimly?
>

Without looking at the schematics I can't tell you if they bothered to put
the resistor in there to make
it glow dimly but I can tell you that it isn't necessary for the run lamp.
The reason to make it glow
dimly when off is to reduce the filament thermal shock when turning on and
off.  This makes the bulbs
last a lot longer.  The run lamp does not flicker in operation so not
necessary on that one.

-- 
Doug Ingraham
PDP-8 SN 1175

Re: Removing Pitting and Rust From an Enclosure

[Doug Ingraham via cctalk]

On Wed, Jul 19, 2017 at 1:52 PM, Rob Jarratt via cctalk <
cctalk@classiccmp.org> wrote:

> The TURBOchannel extender I got has a bit of rust and quite a lot of dark
> pitting on the steel surfaces. I am not sure what the finish is, whether it
> is anodized or galvanized. In any case, does anyone have recommendations
> for
> how to remove the unsightly pitting? Bear in mind that I am in the UK, so
> brands available in the US may not be available here and it may be more
> useful to know what the active ingredients are.
>

I have restored a couple of racks that have been shall we say mistreated.
The
approaches you can use are the same ones that automobile restoration people
use.

Remove the scale.  Steel brush works for this.
Fill the pits.  This might be something as simple as a sandable primer.
Prime.
Paint.

You want to use a primer and paint that is compatible.  If all you are
doing is gloss
black then there is nothing wrong with the Rustoleum product line.  The pro
version
seems to have a little better spray pattern.

There is a point beyond which the only solution is to replace or augment
the material.
You can cut out the sheet metal and weld in a new piece or you can
reinforce with
a fiberglass band aid in some cases.

If the surface is not normally visible you can remove the scale and then use
one of the rust converting primers.  A flat black topcoat will hide almost
anything
that is not directly visible.  Of course this does not apply if you are
trying to do a
museum quality restoration.

Look into restoration videos on youtube for detailed techniques.

-- 
Doug Ingraham
PDP-8 SN 1175

Re: Depressing article

[Doug Ingraham via cctalk]

The amount of data stored on 325 tapes would have been at most 58.5
gigabytes assuming 6250 encoding and single records over the length of the
tape.  Given the time frame I would guess that these were probably only 800
bpi and thus the max would have been 7.5 gigabytes.  And probably at most
half of that even assuming full tapes due to small records and all the
inter record gaps.  After applying modern compression techniques we are
looking at less than a gig of data.  You probably can't find any cute cat
videos on You tube that take that little of space.

What is sad is that some minor functionary was allowed to make the
recommendation to destroy this.

-- 
Doug Ingraham
PDP-8 SN 1175

Re: Teletype 43

[Doug Ingraham via cctalk]

On Tue, May 23, 2017 at 7:20 PM, Jim Brain via cctalk  wrote:

> On 5/23/2017 1:07 AM, dave.g4...@gmail.com wrote:
>
>> You probably need a null modem cable.
>>
> I had one (and used it), but not all null modem cables are evidently the
> same :-)  I soldered up a loopback as you suggested, and the unit dropped
> into DATA MODE on startup.  I then played with the signals.  The unit
> really does want DCD to be active, as just doing CTS/RTS, DTR/DSR, and
> RX/TX did not do the trick.  Evidently, my null modem cable I had tested
> with previously does not connect DCD. Swapped out for a null modem adapter
> (from our old now deceased friend Radio Shack) and the unit works with a
> new Dell M4800 laptop (so "newer" style +-10V RS232 levels must be OK.
>

The minimum legit voltage swing for RS-232 is supposed to be plus and minus
5 volts and the
maximum allowed voltage swing is plus and minus 25 volts.  The problems
occur when gear didn't
bother to do the negative swing to minus 5 volts.  Plus and Minus 10 volts
is more than adequate.


The printer ribbon has less life left in it than I anticipated, but a list
> member is helping me, so it should be good to go after a deep cleaning and
> a light oiling.  I did notice the printhead starts to stutter at times on
> long lines, but I *think* it's a function of the damage to the ribbon, so
> we'll troubleshoot that only if it continues after ribbon fixes.
>

The ribbon on my 43 is a reinking type.  The ribbon loop is maybe 18
inches?  I have a new in bag
ribbon which I am sure is also dried out.  I used a drop of thin oil on the
reinking roller the last time
I messed with it and that seemed to work.  You probably want to use
something that will lubricate
because the pins on the dot matrix print heads do need that to keep them
from rusting and wearing
out.

The "stutter" you mention is normal.  The printer electronics buffers a few
characters during the slow
carriage return and prints slightly faster than 30cps so when a new line is
started it goes at full speed
until the buffer is empty at which point it goes into the stutter mode.
This eliminated the need to send
nulls after a carriage return that was necessary on the earlier purely
mechanical printers.

-- 
Doug Ingraham
PDP-8 SN 1175

Re: PDP Power Usage WAS: BBS software for the PDP 11

[Doug Ingraham via cctalk]

On Fri, May 19, 2017 at 5:18 PM, Ali via cctalk 
wrote:

> > ___
> > The plate on the back of my 11/93 says 345 Watts.  That's about a fifth
> > what your wifes hair dryer draws.  Or slightly more than 3 100 watt
> > light bulbs (which your kids leave on all over the house all the
> > time!!) bill
> >
> > I run a similar PDP-11/83 system 24/7 on a BA23 in a Pedestal stand. It
> > has two 2MB memory boards, an Emulex UC07 connected to two SCSI2SD
> > Cards emulating two RD54s and two RA92s, and a DELQA-T running RSX11M+,
> > DECnet and Johnny Billquist;s TCP/IP and it draws 100-105 watts on my
> > UPS.
>
> Doesn't seem that bad, I am sure some of my vintage servers w/ the 10-12 FH
> SCSI drives, "tons of RAM, and four PPro chips are pulling somewhere along
> those numbers. I may have to invest in a Kill-a-Watt type device to see for
> sure though.
>
> -Ali
>

My PDP-8A with 32k core, RX01 Floppy and an extra serial port card pulls
345 watts.
It would be another 100 if I had not replaced the factory fans with modern
lower
airflow units.  If left on 24/7 this would increase the average power bill
in the US by
about 30 dollars a month.

If you want to run a modern version of a BBS and not have it add
significantly to your
power bill then run it on a modern laptop.  These can pull around 50 watts
when awake
and this would add only a little over $4 to the average power bill in the
US.

For even less power would be to use an Arduino (probably a Due) because
then you are
talking less than 4 watts.  This would be about 35 cents per month.

I wouldn't want to run my Straight 8 24x7.and pay the power bill.

-- 
Doug Ingraham
PDP-8 SN 1175

Re: Need help reproducing a PCB

[Doug Ingraham via cctalk]

If this is a one off all you need to do is print the negatives on
transparency material with a laser printer.
The laser printers tend to have a little more opacity than ink jets do but
I have done this with an ink jet
printer as well.  I also once plotted directly on the bare copper with a
sharpie and had it turn out ok.

Align the negatives on the sensitized board stock.
Expose.
Develop.
Etch.
Drill
Solder in your feed throughs.
Put the parts on the board.
Debug

If on the other hand you want to make even 5 boards you would be better off
with your approach.

Best wishes!

-- 
Doug Ingraham
PDP-8 SN 1175