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IBM Displaywriter

My code was accepted into next MAME release (0.182 -- should happen later this month).

Teledisk and Imagedisk floppy images (single-density ones) are usable with MAME; of those on Bitsavers, C.E. diags and CP/M boot but aren't stable. POST (aka BAT) errors can be skipped with Memory Record button (mapped to SysRq). Product Support Manual is a must read in any case :)

There's still a lot to figure out and emulate, of course:

- verify all frequency sources, document ROM revisions
- memory size options
- bus errors, interrupts

- 92-key keyboard variant, keyboard click/beep, keyboard layouts

- 25-line video board (instant scroll, sub/superscripts, graphics mode)
- 66-line video board

- either emulate floppy board, or complete its HLE (drive select, etc.)
- double density floppies; "memory record" (system dump) generation to floppies

- pass BAT with no errors (Basic Assurance Test)
- pass RNA with no errors (Resident Non-Automatic Test)
- pass PDD with no errors (Problem Determination Disk)
- pass CED with no errors (Customer Engineering Diagnostics)
 
Textpack still does not work in the emulator -- the crash message I've posted earlier means "insufficient memory", even when 320KB is configured. Memory size is actually probed correctly, but is then reset to 128KB -- in the "new" BIOS dumped by Nigel, this happens at FD45Eh.

This code branch is probably taken because several diagnostics still fail (i8255 parallel ports, DMA, floppy) and firmware falls back to using minimum of memory. If I skip the code at FD45E, Textpack loads, draws a part of its UI and then spins waiting for something.

Lots more reverse engineering to do, especially of the floppy controller.
 
nigwil said:
When you get some time could you take pictures of the setup please, and if you are feeling brave please take pictures of the back of the systems and the boards inside.
Click to expand...

So, this weekend we drove to Colorado and picked up the haul. The trip was exciting - we got caught in a white-out and at times the only way to be sure that I was following the road was to put two wheels on the rumble strip!

More detailed pictures, including the insides, will follow as I get to playing with them. For now, here's what I was able to snap while unloading.

I got: Four system units with monitor (one of the monitors has something rattling round inside, but there's a fifth monitor in a factory box, so maybe that's the replacement), two keyboards, one disk drive (no disks inside), three printers (all with rotten foam on the bottom), what looks like a big paper handler, a tractor feed and some cables.

dw1.jpg

dw2.jpg

dw3.jpg

dw4.jpg

dw5.jpg
 
nigwil said:
When you get some time could you take pictures of the setup please, and if you are feeling brave please take pictures of the back of the systems and the boards inside. There is a single screw (slot-type) deep in the hole on the top of the system unit, undo the screw and you can lift off the top of the system unit and you will see the PSU and card cage. You should also look underneath the system unit and see if you have the metal-drawer installed, on some units this has the configuration paperwork (a line-printer printout) tucked inside, this can be equally fascinating about the originally shipped configuration.

We're currently lacking clear pictures of the communications cards that could be optioned with these systems; I'd be glad to find pictures of these boards so I can hunt some down and connect a Displaywriter to a remote system.
Click to expand...

OK, here's the first one. The metal drawers were there, but all the contained was a zip-loc bag holding a piece of cardboard and what I think might be a loopback adapter.

dw6.jpg

Inside, half the space is taken up by the PSU, the rest by a card cage and backplane - which lifts out!

dw7.jpg

The CPU board appears to be on the bottom. There are three other cards:

This one, which connects only to the backplane:

dw8.jpg

The memory card, with stacked ICs (I'm not sure why I didn't photograph the whole thing, when I had it out):

dw9.jpg

And this card, which has a connector going to it, via the other side of the backplane. If this machine has the optional comms card, this might be it:

dw10.jpg

Here's the connector:

dw11.jpg

However, on tracing the wires I find that the two white and three orange wires go the port 2 on the back (DB15) along with four wires from port P2 of the power supply. So comms may be unlikely.

That's all I have for now - it's almost beer o clock!

Edited to add: While putting the monitor back I noticed that it has a DB15 plug, marked 2. So that last one is clearly a video card.
 
Thanks for that. I had assumed that the CPU was in the bottom slot but, according to that, there's a slot below it where the comms card (if present) may be found.

It may take me a little while but, as I have time, I'll look inside all four machines in search of one.
 
Well, I tried powering one of them up. First, I tried with just the monitor connected and got *801* 01 01, as I should have.

Next, I connected the keyboard and got *801* 02 02 - I've been unable to find any reference for that, but knowing my luck it's the memory.

FWIW, I tried again with the disk drive connected. Same error, but the drives did spin!

Also, thanks to a brief look through the customer setup manual (thanks, bitsavers!) I now have a better idea of what I have:
  • 1 Primary system, marked with a P and possessing sockets 6A and 6B, for printer sharing.
  • 2 Secondary systems, with no socket 6s and no socket 4 for comms
  • 1 secondary system, with no socket 6s but with a socket 4 for comms.

So, I'd imagine that that last one should be the next one that I look inside, to see if it has the elusive comms card.

Edited to add: I just looked up the printers, for completeness. Two are model 5218 A01, the third is a 5218 A04, which isn't in the spreadsheet linked to above.
 
OK, today I got into the one with a comms port and I think that I may have some pics of the elusive comms card.

dw12.jpg

The numbers printed on it appear to read 4466897A and MG49083010:

dw13.jpg

Additional observations:

1: There are two ribbon cables connected at the level of the comms card. One, yellow and black, goes to the comms port. The other, orange, goes nowhere.

dw14.jpg

2: IBM must have used different types of memory card. The first machine that I opened had a full length memory card, with stacked ICs, This one has a half length card that looks more like the memory extender card. The numbers on it appear to match those from two of the systems in the spreadsheet. I bet if I checked the other one it would match the other two.

dw15.jpg

Edited to add: I've briefly skimmed a few pages of this manual: https://archive.org/stream/bitsavers_ibm6580DisDisplaywriterCommunicationsServiceManual_10742809/S241-6439-2_Displaywriter_Communications_Service_Manual_Feb83#page/n13/mode/2up

It seems there were several different comms options, some of which involved a second card, in the floppy drive (page 15 on). I shall have to look at the back of my drive, to see whether it has ports 4(a) and 4(b) on the back - if so, I should look inside.
 
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roberttx said:
2: IBM must have used different types of memory card.
Click to expand...

We think 10 types of memory card, have a look at the table on the Systems tab - there are many combinations and sizes of memory card; I have similar to you, the stacked (large-capacity) card and the memory card with the large metal packages (IBM Solid Logic Technology (SLT)).
 
roberttx said:
Well, I tried powering one of them up. First, I tried with just the monitor connected and got *801* 01 01, as I should have.

Next, I connected the keyboard and got *801* 02 02 - I've been unable to find any reference for that, but knowing my luck it's the memory.

FWIW, I tried again with the disk drive connected. Same error, but the drives did spin!
Click to expand...

Disk drives not detected would be the following:

*801* 04 04

However, there could be a problems with drive electronics itself, and it could be the error you are experiencing.

Still - congratulations, and please, keep us updated! I'm pretty sure you will be able to make at least one working machine from them!

If you have 1/2D drive, I can send you a working floppy with a Textpack4 (free of charge).

P.S. Watch out those filter capacitors - they often go up in smoke for machines, which have not been used for a longer time. What is even worse, you do not even need to switch the machine on, in order for them to explode - as long as power cord is connected, they are getting power.
 
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Adventurer said:
Still - congratulations, and please, keep us updated! I'm pretty sure you will be able to make at least one working machine from them!

If you have 1S/2D drive, I can send you a working floppy with a Textpack4 (free of charge).
Click to expand...

Thanks! I'll look for a part number on the drive and see if I can figure out which type I have.

Thus far, the only error codes that I've been able to find online are *801* 01 01 and *801* 04 04. But 01 and 04 imply the existence of 02 and 03, at least, so surely there must be an explanation of them somewhere?
 
roberttx said:
Thanks! I'll look for a part number on the drive and see if I can figure out which type I have.

Thus far, the only error codes that I've been able to find online are *801* 01 01 and *801* 04 04. But 01 and 04 imply the existence of 02 and 03, at least, so surely there must be an explanation of them somewhere?
Click to expand...

I think, that error *801"* means "hardware disconnected'. It is a major code, 02, 03, 04 is a minor code, which indicates a hardware component.

If I'm not mistaken, memory errors start with 901 on a Displaywriter.

You do not need to look for parts number - there should be a label on disk drive closing handles. By the way, they should be open when not in use, yours are closed, at least were in the pictures.

Have you tried other machines?
 
Adventurer said:
I think, that error *801"* means "hardware disconnected'. It is a major code, 02, 03, 04 is a minor code, which indicates a hardware component.

If I'm not mistaken, memory errors start with 901 on a Displaywriter.

You do not need to look for parts number - there should be a label on disk drive closing handles. By the way, they should be open when not in use, yours are closed, at least were in the pictures.

Have you tried other machines?
Click to expand...

Good info, thanks. I'll open the drives next time I pass them and will look for a label.

I've only tried two machines so far and am beginning to wonder whether the keyboards may be faulty - if so, I must have imagined the 02 error.

I really should set aside some time to test everything. If I can get one working system, I can then cycle through each piece in order. That may be a while, though - I'm busy doing my taxes right now (like much of the USA).
 
roberttx said:
Good info, thanks. I'll open the drives next time I pass them and will look for a label.

I've only tried two machines so far and am beginning to wonder whether the keyboards may be faulty - if so, I must have imagined the 02 error.

I really should set aside some time to test everything. If I can get one working system, I can then cycle through each piece in order. That may be a while, though - I'm busy doing my taxes right now (like much of the USA).
Click to expand...

Keyboard error is *801* 01 01, but I think you already know this already. I could not get *801* 02 02 or *801* 03 03, when tried different disconnected hardware - only 01 and 04. By the way, Displaywriter drive motor is directly powered via AC - if it is spinning, it does not automatically means everything is OK with the drive itself. Not just electronics, but drive read/write heads are most likely dirty and unable to read/write anything. If you can spare some time, open the disk drive for cleaning as well - it is easy, there are just two spring screws behind it, and plastic cover comes off.
 
Adventurer said:
Keyboard error is *801* 01 01, but I think you already know this already. I could not get *801* 02 02 or *801* 03 03, when tried different disconnected hardware - only 01 and 04.
Click to expand...

Those were all that I could find, too. I powered up another one today, the Primary system. I wasn't imagining the *801* 02 02 - here's the proof!

dw16.jpg

So, I guess we need to figure out what it means. First step is probably to hook up a printer, but I'll need to clear some space, first!

I also looked at the floppy drive - both drives had a number 1 on the handle. I guess that means they're 1S?

Edited to add: I found a list of BAT error codes in the Displaywriter Product Support Manual (Thanks, Al!). 01 is Keyboard Cable Test, 02 is Physical Keyboard Test. The LEDs were 0110 so it looks like a keyboard issue.

Here's a screen grab:

dw17.jpg
 
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roberttx said:
Those were all that I could find, too. I powered up another one today, the Primary system. I wasn't imagining the *801* 02 02 - here's the proof!

View attachment 37543

So, I guess we need to figure out what it means. First step is probably to hook up a printer, but I'll need to clear some space, first!

I also looked at the floppy drive - both drives had a number 1 on the handle. I guess that means they're 1S?

Edited to add: I found a list of BAT error codes in the Displaywriter Product Support Manual (Thanks, Al!). 01 is Keyboard Cable Test, 02 is Physical Keyboard Test. The LEDs were 0110 so it looks like a keyboard issue.
Click to expand...

Yes, it sems you have a single density drive. In that case my DS/DD floppy will not be much help. You can either make a system with FDADAP adapter and external 8 inch floppy drive, or buy a single density textpack program (it comes on three floppies). Maybe someone else from the forum can help with that?

Do both keyboards have the same problem? Maybe you need to open it up, clean, check for loose connections, and test again? You will need to clean it anyway, since the rubber, which should prevent contamination of beam switches, most likely, is detoriating, and need to be removed anyway.
 
Adventurer said:
Do both keyboards have the same problem? Maybe you need to open it up, clean, check for loose connections, and test again? You will need to clean it anyway, since the rubber, which should prevent contamination of beam switches, most likely, is detoriating, and need to be removed anyway.
Click to expand...

If my memory is correct, yes.

I opened one up today - it's filthy and that looks like mouse poo at the bottom right. I found some useful info over at Deskthority, but I think this is going to take a while...

dw18.jpg
 
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