> I the HP -> Agilent -> Keysight world when you see part numbers start
> with a 0 (zero) in many cases the instrument they were for or in this
> case part of, is the digits that follow.
As I understand the HP numbering scheme
Components have part numbers with 2 groups of 4 digits. The first
> >
> > The original cable, p/n is a 174-1 flat cable with Berg connectors on
> > either end so I had to find something compatible with a terminal instead.
> > I switched in the same BC03L-10 that I have been using to connect to a
> > 25-pin terminal (with null modem adapter) using a newer DL1
> This further helps my understanding. Problem is, the card is bad. Knowing
> it's probably jumpered correctly (assuming I have everything right, which
> is a big assumption) I will check the 1488/89 drivers, etc. to see what's
> wrong with the card.
What I would do is :
Check that there are
> Is the 15kHz RGB signal fundamentally the same as the VGA signal, except
> at a lower horizontal frequency? If not, how do they differ?
Basically, yes. 3 separate analogue video signals, one for each primary
colour.
The drifference might be the sync signals. VGA has two, basically think
of the
> I am in possession of two Magnavox (North American Philips) CM8562
> monitors. Out of the box they handle composite and digital RGBI (CGA)
> input. What I'd like to do is get one to handle analog RGB (like arcade
> boards, Amiga, Atari ST, and Apple IIGS put out). I wouldn't think this was
> poss
> >
> > The ones I have seen are metalised paper and do have a deserved
> > reputation for being antisocial. They split open and emit clouds of
> > evil-smelling magic smoke.
>
> Yep. Famous here in the UK for being used in every single Acorn BBC Micro
> PSU (also ASTEC) plus a lot of monitors and
> Explode? Those are ceramics caps, right? Are these the line inlet
The ones I have seen are metalised paper and do have a deserved
reputation for being antisocial. They split open and emit clouds of
evil-smelling magic smoke.
> filter caps, or later on? For line inlet, you need line rated c
> Does anyone have a VR241 Service Manual?
> I have looked on Manx and BitSavers, but there doesn't seem to be one
> available in those places, and a more general search has failed to turn up
> anything either.
It's also not in (for example) the VT240 manuals. The VR201 is, but said
manuals sp
I am trying to empty my storage unit back to my house (to save money
and becuase I have these old computers to play around with, not to
store). One thing I brought home recently is an old (even on this list)
CRT terminal. It claims to be a Beehive B601.
I have no manuals for it at all.
Inside is
Yes, it's still me. My normal ISP seems to have installed spam
filters (without warning me!) which (a) drop the classiccmp messages
and (b) bounce most outgoing mail!
> On Monday, 30 May 2016, 23:37, shad wrote:
> Hello,
[...]
> the device will be able to control the tape speed and to s
> Of course, rather than expose him to 8088 assembler, I’d recommend
> you run right out and grab a used TRS-80 Color Computer - cheap,
> and 6809 assembly is very very nice - no segment registers.
> The downside of *that* is that if he ever decides to use the “Sign Extend”
> instruction, you
> Are you saying remove all of the GC cards, just leave the slots blank?
Yes, from the slots that are designed to take the core memory or its
controllers (I assume, given you have special backplanes, there are
boards with the core planes on, and more boards with the XY drivers
or the sense/inhib
Strictly the core backplanes are not Unibus backplanes. They have Unibus In
and Out connectors, but the slots are wired for the core memory board,
not Unibus boards (like SPCs -- Small Peripheral Controllers -- which is what
you serial port is).
> Basic Question #1
> Do I need grant cards in *ever
> Using a DW11-B to connect the MINC to a PDP-11/45 sounds fantastic!
Believe-it-or-not I did it becuase I didn't have an RL11. I used the RLV11 in
the
MINC to interface to the RL01s. Yes, that does work.
> What a neat idea! I have all the MINC modules except the MNCTP
> thermocouple inte
Well, the Subject: line gives the result of by decision. I have decided (after
much thought, it was not easy!) to give the surplus MINC to Pete. I wish I had
more spare MINCs so I could give each of you one.
Perhaps the only consolation is that there may well be other machines up for
grabs as I
> Tony,
> Too bad your MINC is so far from me. I would love to have the spare parts
> and RL01s to assist in my MINC restoration.
I think shipping it is out of the question, and there are people interested who
can
collect it from me.
>I would like to collaborate with who ever gets your
> > I am not going to scrap it. It can stay in my Large Machine Room until a
> > good home is found. But I think if somebody can collect it before you,
> > then they are going to get it...
> Not sure I want a whole MINC but a couple of RL02's and controller card
> would be nice for my ex VAX con
>
> How quickly do you need it to be gone? I'd love to have one, but it
> might be a while until I can collect it in the UK...
I feel like saying that 'the sooner the better'. It is not totally urgent, but
I am trying to sort things out...
I am not going to scrap it. It can stay in my Large Mac
> Ue...I have the 4 volume collection...is there another one?!
Apparently, there is. This is really not my area, but I've just
read the titles off the books. All say 'Inside Macintosh' and
'Apple Technical Library' on them. The titles are :
Overview
Processes
Imaging with QuickDraw
PowerPC Syst
I have a DEC MINC that I don't _really_ need and wonder if anyone is
interested.
It's the hard disk model. A half-height rack containing a pair of RL01s
and a power controller with the MINC CPU box bolted on top. It
contains the normal cards :
PDP11/03 CPU
M8044 memory (30kW IIRC)
DLV11-J (4 RS
Still unpacking after a house move 18 months ago... I have found just over
a dozen volumes of Inside Macintosh.
Since programing is not my thing, and I am not into the Macintosh, I don't
really need them. Does anyone want them? Tbey are free, but would have to
be collected from me in SE London (n
>
> 1. Some sites talk about e.g. arcade graphics as being "analog CGA" -- I
> was acquainted with these being called "analog RGB" but never saw "analog"
> and "CGA" together before.
I susepct it means that it's 3 analogue signals (one for each colour) at the
CGA (== US TV, RS170) scan rates. As
> This post: http://www.vcfed.org/forum/archive/index.php/t-16744.html
> Seems to indicate that the Rainbow is a 15khz sync signal, more akin to
The Rainbow outputs a normal RS170-like composite video signal with the
same timings (so 15-odd kHz horizontal, 60Hz vertical). There is a setup
option
>
> All complete and in good cosmetic condition except as noted.
> Assume that they all need repairs.
These are interesting bit-serial 'calculators' built from TTL (mostly). I have
put 'calculators' in quotes because the internal architecture is that of a
computer -- a processor that runs progr
>
> My father is a civil engineer. When I was a little
> kid, he was in the US Air Force. We would frequently
> go to the runway snack bar, get ice cream and watch
> the B-52s do "touch-and-go" landing practice. The
> plane's wings would "flap". It raised the hair on
> the back of my neck. My
[Your VT101 video board]
>
> It's the same board as the VT102, just checked. I can easily check the caps.
>From what I remember there are at least 3 different video boards found in
VT1xx's and any could appear in any model terminal.
-tony
> > Remember one of Don Vonada's laws 'Digital Circuits are made from
> > Analogue Parts'
>
> That's an interesting saying.
Maurice Wilkes (as in EDSAC) once told me 'A digital circuit is like a tame
animal. An analogue circuit is like a wild animal. Every so often the digital
circuit decides to
> Yes indeed. Fortunately this one wielded under my trimmer and all is
> properly aligned now. All I need to do now is troubleshoot the keyboard
> circuit which I hope is the same as the VT102...
Forgot to mention...
The keyboard itself is the same on the VT100, VT101, VT102, etc. The interface
[VT101 with vertical linearity problems]
> Yes indeed. Fortunately this one wielded under my trimmer and all is
> properly aligned now. All I need to do now is troubleshoot the keyboard
> circuit which I hope is the same as the VT102...
In general it is a bad idea to cure faults by adjustments. U
> > Another good practice is to use several carbon-composition resistors in
> > seri$
>
> Actually, that makes me curious. Would a piece of pencil "lead" be a
> workable substitute? I could imagine taking a drafting/art pencil lead
> (the kind that's some 2-3 mm thick) with clip-leads, one on
> > - Since I'm a coder, I understand boolean logic (which I hope would
> > help with ICs).
>
> While it's an understandable point of view, especially for a coder, not
> all ICs are digital logic - and even for those that are, understanding
> non-digital-logic aspects of them can be useful. (I b
> > Actually, many lines of drives, such as the Tandon TM100 have the
> > same circuitry for both the 48tpi and 96tpi variants. (and the
> > TM100-4M at 100tpi)
>
> One of the things that endears to me those pieces of garbage is that
They are considerably better than the Shugart drives with the
> Has anyone ever worked up a PC parallel port to Facit 4070 paper tape
> punch interface?
Are you talking about a modern USB-parallel cable type interface or the
original PC parallel interface where you could individually control all
the lines?
> I found one on a Swedish website. The punch para
>
> I did not know Jon, but wow, what an incredible resource he built for vintage
> HP computer enthusiasts. It would be a big loss to see it go away.
I had never met Jon, but I think it is obvious from the contents of his site
that
we corresponded a few times. He was a great man and will be s
> European tubes are easy to evaluate in that respect because the letter codes
> designate what's inside. I remember the EABC80 (not sure that's the correct
EABC80 _is_ the correct number. It is a triple diode triode. The number decodes
as follows :
E : 6.3V heater
A : diode
B : double diode
> Just for curiosity, which Key codes were used for the PDP-11
> systems? I used to have some PDP-11 racks for RL02 drives
> with a Qbus PDP-11/23 inside and I thought I remembered that
> XX2247 was used on them, but I would just like to know for sure.
> Actually, the more I think about it, just
> Honestly, I can't see the point in modern upgrades except perhaps for
> temporary use in order to get data to/from original equipment. At the point
> where people start adding emulated storage, USB interfaces, VGA display
> hardware etc. it stops being a vintage system and starts being a modern
> Hi,
>
> a recently acquired HP 9845B desktop computer came with a literally broken
> power supply unit.
The HP9845B PSU is very complicated, IIRC it's actually 2 SMPUs and has
various switching regulators on some of the outputs too. It is also painful
to test as you can't get to it when it is
> > > 1) I have a 12 volt DC supply. 12 volts seems to be
> > >within the VIN range for the 7805s whose data
> > >sheets I've now read. Can I simply apply 12 volts?
> >
> > Yes, but that regulator might get mighty hot! I would
> > not do this for fear of cooking the poor thing.
>
> That
>
> First, a few quick "whys":
>
> 1) The 7805 is actually a Motorola MC7805CP, date
>code 7308 with gold leads. Very hard to exactly
>replace.
Any reason why it would have to be an exact replacement?
In any case, the behaviour of the 7805 if you apply a
voltage to the output with the
> If one were to use a dumb CRT terminal from the early '70s regularly in
> this day and age, would it be more prone to hardware failure than if it
> were kept in storage or just kept to look at but powered off?
If you never turn it on, how will you know if the hardware has failed?
More seriiousl
>
> This particular 3a has no horizontal scan. None at all. I just get a
> vertical line down the center of the screen. First thing I checked was
> the horizontal deflector on the yoke, which seems secure.
I am going to assume this is a conventional design, I would be very
surprised if not. In wh
>
> The "SL0227 / 404780" part appears to be a Zilog Z80 CPU of some kind,
The '404780' number looks a bit like a Teletype part number...
IIRC the Z80 has very odd positions for the power and ground pins, you
should be able to verify that it is a Z80 from that. Then stick a 'scope
or counter on
>
> Also also possibly any help - I used a VR241 monitor on an Amiga 500 for
> years with a cable I knocked up out of a VAXstation monitor cable and a
> 23-pin clamshell which was almost unobtanium in those days, so if you have a
> monitor that works with an A500 you stand a chance of getting it w
>
> I could do with getting hold of a VR241, but these seem to be pretty
> unobtainable. So the alternative is to rig up an adapter of some kind to
> work with a VGA LCD, which also saves on space. I came across the following:
> http://www.vcfed.org/forum/showthread.php?38450-VR241-substitute-for-
> > Could they be 3d printed? Pictures might help...
>
> There are actually two varieties. The plastic ones probably could, but
> actually I was
> talking about the steel ones which probably can't. I have put it all away
> again for
> now so I can't get any pictures right now. I'll get it out
>
> I just acquired one of the guys w/o a display
>
> Looking for the spec's of the display connector.
>
> I have what I believe to be the pinout but nothing on timing, scan rates,
> levels etc.
If it is a CU -- that is it has a colour video board set in it -- then it is a
bit
strange. There a
> Tony, reverse engineered the HP 9836C (and a lot of other HP equipment) he
> made the diagrams available through the HPCC.
> It's part from a great collection of HP diagrams including calculators
> computers
> and peripherals etc.. http://www.hpcc.org/cdroms/index.html
It was decided by the
> It's now foggy memory, but I'm pretty sure HP 7900A (and 7901) were using
> batteries for emergency head retract.
The 7900 certainly does (there is one to go on my bench when I have some
spare time). In that case it's some AA-size NiCds (not tagged ones) in those
aluminium clip-in holders (Radi
> Anyone have any idea on how they handled this? I'm thinking of using
> some blocking and then a 36 or 48" pipe clamp to apply diagonal
> persuasion to get it back in true.
In general screw-type mechanisms are good for providing controllable force
for jobs like this. I've used a screw-operated
> > The original resistor (as mentioned in the Subject: line) was one of those
> > safety fusible
> > resistors. AFAIK none of the ones that Farnell stock are.
>
> Oops, I missed that part of the subject line. It'll be fusible for a
> reason, so should be replaced with the same type. Moreover,
> No, sorry, but Farnell do:
>
> http://uk.farnell.com/webapp/wcs/stores/servlet/Search?catalogId=15001&langId=44&storeId=10151&categoryId=70005447&st=resistor%202W&pageSize=25&showResults=true&sf=502&pf=110030112,110046859
>
The original resistor (as mentioned in the Subject: line) was one
> In my continuing quest for a 9-track drive I got my hands on DEC TSZ07-CA w/
> a narrow SCSI interface that was supposedly "tested working". On arrival to
> me I found it wrapped in a thin layer of bubble wrap w/ some broken piece of
> Styrofoam thrown in for "packing".
This looks very like a Ci
>
> FWIW, the IBM term for "motherboard" was "planar", at least in the era of
> the PC, PC/XT, PC/AT, etc.
But IBM (at that time) also used the term 'Planar' for 'backplane'. The
backplane
in the 5161 expansion unit [1] is labelled 'I/O Planar' or something very
similar
in the silkscreen.
[1]
>
> I've always eyed the 4952... being as my penchant is HP and much of my test
> equipment is same-vintage HP gear (I'll give a vote for the 1631D logic
> analyzer, combo LA and digital scope - the scope is sorta poor, but handy -
> the LA is great for what I work on).
I would love to find the u
>
> You could use something like an Arduino to buffer
> either. It could take the 9600 from the terminal and
> retransmit it at 110. It would be slow when updating
> data to the terminal but it should be able to buffer human
> input at the terminal.
If you're going to keep the PDP11 port at 110 b
> >
> > I have found that those little in-line RS232 testers with 7 or so bicolour
> > LEDs monitoring the important signals are very useful when working on
> > a machine with a serial terminal. If you get flickering on the TxD or RxD
> > LEDs then it is sending something.
>
> Yes and I usually us
>
> That's my understanding too - complicated by the fact that are two
> Tx/Rx pairs for the two drives IIRC...
No it's just one pair, to pne controller board (fitted on top of the drive
module). The commands specify which drive is to be used.
-tony
> > On Feb 21, 2016, at 14:41 , Mike Ross wrote:
> > Thanks for that. Are you able to provide confirmed working details &
> > pinouts for the cable? IIRC it was just three wire; Rx/Tx/Gnd? Would
> > help if I could have confirmed working setup there.
>
> I'll need to dig inside my machine to veri
>
> Which is your favourite ? Why you like it and would recommend it ? and
> How often you use it ?
Does the HP LogicDart count? (it is a 3 channel logic analyser)
If so, then it's my favourite, its so convenient (not much more work than a
simple
logic probe, but it tells me so much mor
>
> It's a 4000/60, I'm afraid it's untested, and Farnborough is just
> outside London England.
Be careful. There are several Farnboroughs in England, and the one
'just outside London' is almost certainly not the one you mean. The
'just outside London' one for me is between Bromley and Green
Stre
> Well I haven't figured out exactly what the problem was but I'm
> embarrassed to report it was indeed serial comms finger trouble. I
I have found that those little in-line RS232 testers with 7 or so bicolour
LEDs monitoring the important signals are very useful when working on
a machine with a
>
> I just double checked. 3 was open; 4 was closed. That's default 2400.
OK...
Just to confirm, this is the DIP switch near the middle of the board, not the
one in one corner near the BERG plugs for the serial cables. The latter
is involved with the handshake lines for the remote diagnostic
[...]
> red lights. The baud rate switches are set for 4800 - the default.
Eh? There is no way to set it for 4800 baud (the installation manual,
printset, and my tests all agree on what baud rates are available).
How do you have the switches set?
Note that if switch 2 (of the DIP switch at lo
> > Of course I don't know mine works, I need to get a working TU58 tape...
Perhaps I should have been a bit clearer, it does pass the console POST,
then gives read errors on both drives (as there is no tape in them), then
gives the ROM> prompt. So mine is getting further than yours, but until
I
>
> See row of red LEDs on M8391? On power-up the leftmost LED lights and
> goes out. Then the rightmost two LEDs light and stay on...
I can't remember exactly what mine does, but I do remember 2 LEDs at one
end being on when it settles down. So I think yours is probably OK.
Of course I don't k
> Just started working on mine - been a back-burnered project for a long
> time. Unfortunately all the cables were cut when it was dismantled; I
> was lucky to grab just the CPU.
I had to re-fit all the cables on mine (a painful job), but at least I had them
all, uncut.
> Got it powered up ok -
>
> Peter,
>
> I confirmed that there is a NCR5380 chip on the daughterboard and that
> everything was connected. Still no joy. The one thing I'm wondering is
> this. If you look at the attached picture below from
> http://home.iae.nl/users/pb0aia/vax/vs3khw.html, you will see there is a
> 40-
>
> Yep. The boards were used in the 11/70, the 11/730, and the 11/750.
> I don't know if
> you could use the 256K boards (populated with 4116s) in the 11/730 due
> to the tri-voltage
> 4116s, but even if they worked, you wouldn't want to - 5 of them just
> isn't that much RAM.
I am pretty sure
>
> I have one of these on my restoration list. I know the PSU does not work, and
> that others
> have tried to fix it before me, who probably know PSUs much better than I do.
> It has core
> memory so I really would like to get his one fixed. I have never seen a PSU
> for it come
> available
>
> > I heard that when Bristol University physics department got its first VAX
> > (an 11/750,
> > somewhat before my time), it was cheaper to buy 256K memory boards full of
> > 16K RAM
> > chips, clip them out, clean out the holes and solder in 64K RAMs rather
> > than to buy 1MByte
> > board
> > First week on the job in March 1980, my new boss brought me two pdp11/04s
> > and a box of memeory chips. He to told me to double the memory in
> > the two computers by populating all the empty holes on the memory boards.
>
> I had a boss in 1987 that asked the same of me...
I heard that whe
> > So, how do you deal with your 8" drives, and what do you do when
> > they don't work?
>
> Don't get into the alignment issue without a scope and an alignment
> disk--once you loosen the stepper motors, it's a very touchy operation
> getting them back into position, even with a special (expens
> Over the years I have learned a lot and would like to particularly express
> my thanks to Tony Duell, Fred Cisin and Chuck Guzis for being unfailingly
> polite and very forthcoming with technical advice.
That is the first time I have been called 'polite'. You've n
> I recently picked up an HP 9815s ( was originally an 'a' model but was
> upgraded with an 's' cpu board and the option 002 i/o long before me), that
> displays the "---" when turned on. I've scrounged through
> Google and learned that this particular display is generated by the disp
[IBM PC ROM BASIC]
> Well it would, otherwise IBM DOS Basic wouldn't work
.> .. it checks for the Basic ROMS and won't run on a clone...
Not so much 'checks for them' as 'uses large numbers of
routines from them'. The BASIC on an IBM PC-DOS disk is
a much smaller file than the one on a norm
>
> You, should read the article series "Liebson on IO" about the HP 98X5 IO.
> And processor manual from the BPC on HP9825.NET.
Do not forget the HP75C ROM source code...
-tony
> I thought HP manuals were dry and hard to read, but I was wrong. See for
> yourself...
I've found more jokes in technical/service manuals.
Take a look at the HP1311B XY display manual, the EHT power supply section :
page 151 of the pdf on hpmuseum.net.
-tony
>
> Considering DEC did something like this for the DWBUA, but with 4
> 30-pin cables (by necessity because of the BI backplane), is 2x60 pins
DEC (also?) made a board that brought the Unibus out on 3 40-way
cahles. The 11/730 I am restoring originally had a Unibus expansion
cabinet, and the arra
As I mentioned some time back, I am currently restoring a VAX 11/730 system. It
is the version
with the TS05 on the top, I currently have the TS05 in many bits while I sort
out at least 4 faults
with it (No, I've not sorted out the TU58 console tape drive yet, I needed
something else to get
on w
> The other thing to be aware of is the emergency head retract batteries are
> toast and should
> be replaced with a 3.6v NiCd pack, that way if the power fails you don't
> trash a pack.
I thought originally it was a 4.8V pack (4 cells). Over here a common cordless
telephone used the
same pac
>
> This one looks like it's in really good condition, but I have read about
> those issues. I'm just going to monitor it closely when initially mounting
> packs to verify the seals and integrity. As much as I hate to do so, I know
> it's common to run these without the top cover on for calibratio
>
> It's a well-known fault, but has anyone ever known one fail and actually
> cause any damage (other than to itself)? AIUI, they're there to reduce
Not really. Maybe a blown fuse. I have had the live-earth capacitor in a filter
fail and trip the RCD in my consumer unit (meaning I was in the da
>
> Well. It depends if you read the schematics before you do so. In this case
> I powered the startup voltage from a 12 V bench supply. Normally the
> startup voltage comes from a small mains transformer and a 7812. Then I
> supplied the primary side voltage for the main switch transistor using a
> Ideally I would like to find the following:
> 7009026 Cable which is two ribbon cables with a M933B or C flip chip on the
> other end
> The interface cable between the two drives: BC11A
> The terminator card M930
>
> At minimum, I'm pretty sure I'd only need the first cable to run one of the
>
> Just for my understanding: if I do the math: 512 pixels x 400 rows = 204'800
> pixels
> at 50 Hz I end up with 10.2 MHz and at 60 Hz = 12.3 MHz.
> There is more "room" required for the retrace time, probably another 10% or
> so?
To avoid the inaccuracies from the unknown vertical retrace time
You missed out
STRING AND SEALING VAX : What you need to kludge up a solution to just about
any problem.
-tony
> indeed this machine has a 98204B video board (intended to work with a 35721
> monitor,
> which I don't have). I have not yet found the specs for its composite signal.
It is normal composite video voltage levels with faster-than-normal horizontal
scan rate.
If you have a frequency counter (o
IF the PC100-A is like the PC100-B (which I have full schematics for)...
> All LEDs on, means, "replace the system board".
>
> I'm not sure, he wanted to hear that ;-)
And it's not even right!. You can have all LEDs on with a perfectly good
system board. A fault in the power-OK circuit in the P
I think I have had a most instructive day. I did what I should have done a lot
earlier and connected
a (cheap, built from a Velleman kit) DSO to the output of the read amplifier in
my TU58. That's
pin 6 of the CA3130 at location E28 if you are trying to follow along in the
printset, The printset
>
> Yeah, but if the emulator doesn't work,
> then you have another important clue.
I _know_ there are problems on the TU58. It should detect the BOT and EOT
markers and not let the tape run off the spool. It should never produce the
waveform I am seeing at the output of the read comparator. No
>
> What's the SD card based TU58 emulator that a couple of people mentioned?
> Is that just a Raspberry PI with linux and the existing TU58 emulator
> software, or is there something more purpose built?
First hit on Google for 'TU58 Emulator' (no quotes) for me was :
http://www.torok.info/co
>
> On a VAX, there is an application (named EXCHANGE if I remember
> correctly) which reads and writes the first partition of any RT-11 disk
Err, yes... This implies I have a working VAX. Until I repair ths TU58 and get
it to load the CPU microcode, I don't.
Sure...
> If you have a PDP-11 syst
> If it were me, I'd start by setting up some tests to determine what exactly
> the protocol analyzer is doing. If it really is dropping 0 bytes, then I'd
Well, I see 2 ways forward, in that I have found 2 things that look odd...
One is to investigate the serial link between the VAX console pro
> While the TU-58 tape will not have an RT-11 file
> structure, you can at least read each raw block
> and display the contents:
Actually I believe the VAX11/730 console tape is an
RT11 file system (for all there is no PDP11 involved).
-tony
> Moral objections have nothing to do with getting as many tools on a
> problem as you can.
True. But if you don't have said tools set up and working, you may find
(or at least I will find) that when somethng doesn't work you are not sure
if the problem is a genuine fault or misuse/misunderstandi
>
> I can certainly understand that. But a TU58 emulator could be a useful
> diagnostic tool. Personally, I would try to get it working from the
Agreed. But a diagnostic tool is only useful if you can trust it. I suspect
that if
I tried to set up a TU58 emulator I would have problems due to m
>
> > I had considered that, or one of the TU58 emulators that use SD cards or
> > similar but (a) I am trying to restore this VAX, not make a machine that
> > runs
> > VAX software and is not original and (b) I do have this moral objection to
> > using more components to load the microcode than
> 800 BPI (NRZI) only has transitions on a data track when
As I understand it the TU58 is not NRZI.
According to the manual (and I see this sometimes) a 'bit cell'
starts with a +ve magnetic flux transition (OK, that is meaningless,
it really means there is a +ve edge at the output of the read
co
> >
> > Powering up gives the expected ROM> prompt on the terminal. Of course all
> > you can
> > do at that prompt is load the microcode from the TU58, so that is what I
> > am trying to
> > get working. And getting nowhere!
> >
>
> And you don't want to use a TU58 emulator? (Or you enjoy waitin
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