IBM Displaywriter 6580 journey

[mt777]

Locally bought rusted Displaywriter set without keyboard (unit / monitor / floppy drive). As no signs of life then decided to find another working unit and do inspections.
Found nice set in germany with keyboard and printer. Also got extra set but based on 110V.
Then having 3 sets I could do some tests...


Here is log, maybe someone more experienced will share with his thoughts, before will do assembling back:

Set1: bought locally. Unit + Monitor + Floppy drive. 220V
- motherboard: NOT WORK
- video card: once booted with solid background, later anymore
- memory card: 224KB. OK
- extended memory card: 64KB. OK
- floppy. 2x double sided. Noisy but works
- monitor: ok
- PSU: `A` LED

Set2: Unit + Monitor + Keyboard + Floppy drive. 220v
- memory card: 256KB. OK
- comm card (long), extra purpose? difference between short/half version?
- video card: ok
- motherboard: ok
- monitor: ok
- floppy: single sided + double sided. Silently works

Set3: Unit + Monitor + Floppy drive. 110v
- memory card: 256KB
- comm card (short) ?
- video card: ok
- monitor: ok
- motherboard: ok
- floppy. 2x single sided. Silently NOT WORK. No reaction after inserting disk

Printer. I pushed Print Test then caret moved to the left and center. After that something cracked and smoked...

Extended memory card I upgraded from 64KB (2x32) to 160KB (5x32) and setting (removing) jumpers. Then DW boots and reports 416KB memory.
So from local rusty unit I found valuable? extender memory card and had donor memories from main card.

Photos: https://drive.vtgpc.com/index.php/s/ScarZMqDNXgQn07

 

[Al Kossow]

very little is known about the printer, since so few people saved them
there is quite a bit of intelligence inside of them

 

[RetroAND]

Due to the Datamaster sharing the list of ofuscated integrated circuits, I had to cross some lists and also found a couple of them on my own. Also found were values for some resistor packs and capacitors.

If you don't find a reference feel free to ask.

 

[Chuck(G)]

What Al said--back around 2007, I started tackling the DisplayWriter disks and operation. What I found was that some printer codes were common to the DW on-disk storage.

Was the DW printer peculiar to that system or was it used on others?

 

[mt777]

Printer was used with this system - it is even on youtube by previous owner. But before will try check what happened with printer, then want assembly back main units.
Anyone know what is difference between serial cards?

 

[RetroAND]

Printer was used with this system - it is even on youtube by previous owner. But before will try check what happened with printer, then want assembly back main units.
Anyone know what is difference between serial cards?

Take this as a grain of salt because I cannot find the main list of cross-references at this moment:

It is like if they removed the 8250 UARTs and replaced them with 8251 USARTs, keeping a 8253 PIT to generate the baud rate. The large board seems to already contain an USART(?).
In my humble opinion, the short version could be a later, cost reduced version of the large one.

I will try to find the list so this could be left as a conjecture or accepted as a fact.

######## EDIT ########
I found the list at http://www.bitsavers.org/pdf/ibm/logic/IBM_Part_Number_to_Industry_Part_Number.txt

As I suspected, the short board contains two USART (8251/4178619) and a PIT (8253/4178625) while the longer one contains a PIT (8253/4178625), an USART (8251/4178619) and two SDLC controllers (8273 SDLC PROG CONT/4178624)

Basically the shorter one may let you interface the system using standard protocols and the larger would also let you interface the Display Writer with twinax(?).

 

[mt777]

Thanks for explanation...
Are these 64KB/32KB memories are needed elsewhere (in other machines) critically?
To know what should I keep in collection or spare parts for future purposes.

One extra problem related to floppy drive propably solved. AC adapter from 230->110 needs also frequency (60Hz) adjustment.

 

[RetroAND]

Thanks for explanation...
Are these 64KB/32KB memories are needed elsewhere (in other machines) critically?
To know what should I keep in collection or spare parts for future purposes.

One extra problem related to floppy drive propably solved. AC adapter from 230->110 needs also frequency (60Hz) adjustment.

Sorry, I cannot answer that question... Maybe the System/36 but I don't really know... I don't remember having seen the 5363 having DIP-packaged memories, therefore there's a possibility.
My piece of advice would be to keep in case of doubt - one never knows what or when a failure can occur. I normally use the rule of three units: one for display, another to use and a third for spares. The first two need to be working and the second may be modified for ease of use while the third is not required to be in order.