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Mystery ISA card with z80

offensive_Jerk

offensive_Jerk

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I got this card from someone who said it's from an XT.

It's got a battery on it, a z80, appears to be 256k of memory.

It also has some sort of ROM with adapter.

ROM is labeled DG/PC-6
900145-018
5250

There is a sticker on the slot that says
327
DG/PC-6
900157-000
5250
Has a 60 pin female connector on the back.
 

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It has three dual-port Zilog SCC serial chips on it, so I would guess it’s some kind of intelligent terminal/modem control board, or possibly even a network hub. (Those SCC chips are very sophisticated compared to the standard PC UARTs; for instance, Apple Macintoshes used them for AppleTalk/LocalTalk networking.)

Whatever it is I’m sure it’s useless without whatever it was supposed to be cabled to. As for the ROM chip, it probably holds code for the Z80, not a BIOS extension.
 
I googled "5250" and turns out it's some kind of block terminal, but this connector seems like a lot of pins for that.

I was thinking some kind of mainframe/terminal card, but then started wondering if it was a CP/M machine on a card or something.
 
MC145406 is an RS-232 driver chip, and there are oodles of them. What's interesting is the empty 8-pin sockets. Perhaps it was designed for RS-485 as an option and it's basically just a 6-port high-speed serial card, with an octopus cable plugged into the port. And it's got 256K of RAM? That's a lot of buffering. I also notice it uses 74F logic, so it's definitely some kind of hot rod design.

A dump of the EPROM might reveal some of the mysteries.
 
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The 8 pin sockets could well be for optional differential signalling; e.g. SN75117. Hard to say.
What's puzzling is the battery. I don't see a clock chip or SRAM chip anywhere (maybe I'm missing it).
 
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It also came with this mainframe/terminal card. I am under the impression I got everything from the xt it came out of minus the case and motherboard. I am tempted to see if the hard drive works if any software is on it.
 

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Well, the Seagate drive that came with this package seems FUBAR. Sounds like a nasty scraping head crash. The scraping noise seems to have gone away but I can hear the head knocking like it can't find track 0.

It won't boot.

There goes that option.
 
You could try pinging Digi technical support asking them if they have any manuals or software for a "PC-6" and see if you hit the jackpot.

The vibe I get from this thing is it probably *didn't* come from an XT; digi was selling multiport serial boards like this with ISA connectors (8-bit, no less) well into the 1990's, and I'm not sure that an XT would be enough computer to meaningfully support what you'd be *doing* with this. (Typical uses for this would be to drive a bank of modems or local serial terminals for a multiuser UNIX system or whatever.) But, who knows, people do weird things.
 
Looks like the smaller digichannel (approximately 8 port) devices had pretty simple looking breakout devices:

www.recycledgoods.com

Digiboard 8 port RJ-45 Cable Connector (Digi)

Shop The Digiboard 8 port RJ-45 Cable Connector (Digi) , Quality Checked, Fast Shipping.
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digiboard-8-port-rj-45-cable-connector-digi-1.39__42540.jpg
digiboard-8-port-rj-45-cable-connector-digi-5.39__28349.jpg
digiboard-8-port-rj-45-cable-connector-digi-6.39__62888.jpg

the 16 channel devices seem to have a big box.

I wonder if the 6 channel version has something small like the 8 channel.
 
Chuck(G) said:
The 8 pin sockets could well be for optional differential signalling; e.g. SN75117. Hard to say.
What's puzzling is the battery. I don't see a clock chip or SRAM chip anywhere (maybe I'm missing it).
Click to expand...

The presumably battery backed SRAM chip is hidden underneath the ERPOM. Zoom in and it is visible by C23 and C24.

Or possibly the hidden chip might be also have an RTC function. To the left of C23 there is an X component, which might be a common 32.768 KHz RTC crystal.
 
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Yup, my bet is that it is Digi's answer to the Comtrol RocketPort EXPRESS card which is a multi-port serial interface card for use in a XT or AT running Unix or Xenix or some equivalent multi-user operating system. Xenix was to more popular for the smaller architecture of the 86/88 that has a striking resemblance to Unix, perverted by Microsoft. The adapter with the 64pin connecter fans out all the ports to DTE configuration. Some may also have RI pin for modem incoming call detection.
Just my $.02.
W1ARQ
 
Bingo, a clock chip, hence the battery.......

The 58167 also has a few bytes of battery backed ram for keeping tid-bits of config info for the card when the power is off.....
all of which I suspect is unavailable to the host (PC) directly because it wouldn't know how to execute Z80 code, the Z80 does all the legwork. The Z80 just does all the running around maintaining the serial ports, make data available to the host (PC).
What you have is a Z80 SBC with several serial ports and a battery backed RTC, that will plug into an ISA bus, and if you cared to, you could poke around on the PC looking for these "ports" that the Z80
maintains for the HOST, or reverse engineer the ISA bus pins to determine which ports are active.....
 
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