IBM 524x Printer Emulation

[NeXT]

My Datamaster did not come with the listed 5241 or 5242 printer and while I am looking to source a printer since the system has almost no other output devices beyond the monitor I'm tight space to put it near the system and am wondering how trivial it is to substitute with something else.

The service manual is polite enough to give you pinout details of the printer port but not a technical section for the printers. ISTR the Printers are recycled mechs from elsewhere in IBM's lineup but I'm not entirely sure if they are interface or electronically compatible. The service manuals also do not seem to be on Bitsavers either, so we only got one snippet of information.



What can we tell from this:
1/2 signal to printer is either differential or twisted pair grounded
3/4 signal from printer is either differential or twisted pair grounded
5/6 self-explanatory.
7-9 Likely a 3-bit parity selection to alter the port speed. Are they jumpered to ground within the connector? Does the presence of an of the three being pulled low tell the system a printer is attached?

So it's a serial interface, not parallel like the later 5150.
Anyone else have anything to add?

 

[Al Kossow]

the displaywriter printers were also serial.

the 5217 was sold with the displaywriter as well, here is the pinout on the displaywriter

 

[NeXT]

What's interesting about the 5217 is it's absent from the 1981 Datapro report and by 1984 it's listed as available as a $4400 option.

 

[Al Kossow]

I don't think the 5217 existed in 1981 did it? Displaywriters originally shipped with selectric mechanisms.
I'd have to dig around to see when the Datamaster word processing product came out, which I assume
required the 5217 Wheelwriter printer.

Service documentation for any of the serial printers would be nice to find. I'm trying to get some 5218 docs on loan right now

 

[RetroAND]

When they said "{place anything here} return" in the case of the Datamaster they refer to GND. At least it was when I built the composite video adapter I use to test the system at the bench.

 

[RetroAND]

I forgot to mention something important about my latest post. There is an optocoupler in the board located near the corner where the serial connector is. I can only assume that the "Received data return" won't be connected to ground as it may be optoisolated from the Datamaster.

I have to identify what optoisolator is, I got a datasheet from the era of HP optical products and with that I reduced the options to a very few. Now, only by the context we will learn which of them is the one at the Datamaster.

EDIT

Look, to use the 5217 the second printer interface is needed! This means it may not be used with this interface.

 

[traveler_aa5]

I worked on the code in the 5242. The first thing I was assigned was to fix what was called "the sleepy printer problem". Now and then, the printer would just stop, with the stepper motor controlling the paper advance locked. There had been several previous attempts to fix it, but they all failed. The main problem was that the interrupts for the print head and paper advance were shared. The paper advance interrupt would be missed. I had about 50 bytes to fix it. The previous attempts had attempted to fix timing issues with the interrupts. I took a difference approach. If a print wire was printed, I checked the paper advance interrupt. If it hadn't been seen, I assumed it had been missed, so I marked the interrupt as being received. No more locking up. It used an 8085, and I built the code on an Intel iPDS.

 

[traveler_aa5]

I just saw the comment about the mechanisms being shared with other printers. There were several printers that had similar mechanisms (5241,5242,4974,4975,5256,3287, maybe more). Although the mechanisms were similar, there were a fair number of mechanical differences. Even the processors used were different. I wasn't familiar with the 5256. The 524x and 497x printers used an Intel 8085 processor, and were developed in Boca Raton. The 3287 used a IBM UC.0 processor, and was developed in RTP.