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Xerox 820-II revival!

xmechanic

xmechanic

Member
Joined
Dec 27, 2010
Messages
29
Location
Reserve, NM (USA)
Well, after 10 years or so of sitting in my back room basically untouched, I got my neighbor kid to come and help me move the 820-II back to my workbench/kitchen table, and proceeded to do a deep clean and inspection of everything before trying to restart it. I borrowed a variac from a friend of mine to bring the power up slowly, so as not to shock load all the capacitors, and then rebooted at full power, and everything came back up like it should. The HDD is fine, 8 in. floppy is fine, and life is good! 😁 Plus, the flyback transformer in the monitor doesn't squeal anymore?! Maybe the electronic fairy has been here at some point in the recent past?😄 Anyway, once I relearned some of the commands, and got the sticky keyboard to play nice, I loaded SuperCalc 3 and a working database, and all seems well!

20231206_133617.jpg20231206_133637.jpg
 
That's awesome!

Ask the neighbor kid if he can hear the flyback :)

I have that same main unit but no keyboard or 8" drive bay. It's dead unfortunately so it needs some troubleshooting. Once I get it to where it powers up, I'll build a keyboard for it and use it as a serial terminal. Then I'll go hunting for an FDC board for it since mine has the hard disk adapter instead.

It's a wonderful machine and wish I still had mine from back in the day.
 
Amardeep-AC9MF said:
That's awesome!

Ask the neighbor kid if he can hear the flyback :)

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LOL, surprisingly, my high frequency hearing is still pretty good! I can still hear higher frequency sounds better than people much younger than me. Plus I live in a pretty remote area, so I'm more tuned into sounds around me. That said, the flyback has been behaving itself very well. I had it up for almost 3 hours today, and before it would start squealing after 20 minutes or so.🤷‍♂️ and it was LOUD!

I want to eventually look into what printers it will emulate, and see about maybe building some sort of interface for a working Epson dot-matrix printer that I still have. So far, all the programs I previously installed are still working (except for Kermit 4.11, which I could never seem to get debugged). Not really a big deal, as I came up with a DOS-based program running on Windows 98, to write to the 8" floppy discs directly through a home built interface cable. Much quicker, and more accurate than trying to transfer files between a pair of modems.;)
 
Nice. Each CP/M program sort of handled its own printer drivers, but most had some sort of Epson support so you should be good. There is a header just inside the back edge of the system board for connecting a Centronics printer. They didn't bring it out to the I/O panel since the original Diablo daisy wheel sold with the system was a serial interface. There was some kind of cable kit they sold if you wanted to use parallel but it should be easy enough to fabricate.
 

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Amardeep-AC9MF said:
Nice. Each CP/M program sort of handled its own printer drivers, but most had some sort of Epson support so you should be good. There is a header just inside the back edge of the system board for connecting a Centronics printer. They didn't bring it out to the I/O panel since the original Diablo daisy wheel sold with the system was a serial interface. There was some kind of cable kit they sold if you wanted to use parallel but it should be easy enough to fabricate.
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Ahh yes! I see that now. I actually have a Centronics cable and header to run a parallel port out the back of the case. I don't have any schematics for the board, but I'm assuming the pinout is the same as a standard 'LPT1' parallel port?
fritzeflink said:
Nice. On bitsavers there are a mass of xerox820 imd images and I did some extracting with dir and file listing for them years ago.

Please look at:

oldcomputers-ddns.org/public/pub/rechner/xerox/820/
oldcomputers-ddns.org/public/pub/rechner/xerox/820/imd/
oldcomputers-ddns.org/public/pub/rechner/xerox/820/imd/image_and_files/box1/
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Excellent!! Thank you @fritzeflink ;)
 
I don't know if the parallel printer port pinout matches what IBM PC and clones typically use. Probably not since IBM used 26 pins and Centronics ports were 36 pins. I think the Xerox header is the latter. But the schematics are definitely available at the bitsavers link above.
 
The internal parallel port was also used to interface with a Corvus 'flat-cable' drive. I have such a setup here and it's a fun combination. The network interface box is quite simple and would be easy to clone.
 
shirsch said:
The internal parallel port was also used to interface with a Corvus 'flat-cable' drive. I have such a setup here and it's a fun combination. The network interface box is quite simple and would be easy to clone.
Click to expand...
Would that be similar to the Kaypro, which used a WD parallel - ST212 controller board?
 
No, the only similarity is the fact that they transmit parallel data. Corvus had their own proprietary signaling scheme and API.
 
Great, the 820 is a good solid, yet boring-looking, machine.
I've got one with dual floppy drives, and 2 with hard drives but neither of the hard disks work.
There's an 820 group on FB.
 
Ragnarock said:
Great, the 820 is a good solid, yet boring-looking, machine.
I've got one with dual floppy drives, and 2 with hard drives but neither of the hard disks work.
There's an 820 group on FB.
Click to expand...
Oh, nice. I'll join up in that group. Once I have the machine fixed enough that it beeps at startup and gets something on the display, I'll need a floppy controller for it.
 
Ragnarock said:
Great, the 820 is a good solid, yet boring-looking, machine.
I've got one with dual floppy drives, and 2 with hard drives but neither of the hard disks work.
There's an 820 group on FB.
Click to expand...
I just searched FB groups and cannot seem to find it. Do you have a link?
 
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