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Persyst Time Spectrum card - LPT port fault

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3pcedev

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Jun 8, 2014
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Hi all,

I have a Persyst Time Spectrum card installed in my IBM 5160. I was using the LPT port on the board to transfer some files tonight (using FX) with no problems at all.

I powered off the system and powered up again. I then discovered that FX would not connect to my other PC. Upon further investigation I found that FX was not even detecting the LPT port (if you go into diagnostics it will list all the ports available).

FX listed both the com port on the Time Spectrum card & the other com port present on another card but no LPT port?

I tried the usual re-seating the card, reseating the IC's etc. Still nothing. Not sure why it decided to just suddenly fail....

Anyone got any ideas? The fact that it can't even detect the presence of an LPT port is somewhat strange; usually they just fail when reading/writing to them.
 
Did you triple-check the jumpers? The Persyst card appears to have a lot of them. Otherwise, I'm fairly certain that the printer port uses the standard SSI TTL, so it should be pretty easy to troubleshoot, particularly if you have a logic probe.
 
Hmm gave the switches a rock and also plugged/unplugged the jumpers a few times for good measure. No difference.

You wouldn't happen to know what the switches/jumper assignments are? I have no documentation despite an extensive web search. I can then attempt to change the LPT address.

BTW Its a Time Spectrum 384L. I can take a photo if it will be of assistance.
 
3pcedev said:
You wouldn't happen to know what the switches/jumper assignments are?
Click to expand...
No. All I have is the card's clock program, which you would have seen on my web site.

3pcedev said:
BTW Its a Time Spectrum 384L. I can take a photo if it will be of assistance.
Click to expand...
It would not help for switch/jumper settings, because switches and jumpers can be located far from the circuitry that they control.

If your card is like one I can see on eBay, then there are only two large chips, an 8250 UART for the serial port, and a 58167 RTC chip. That would mean that the parallel port is implemented via some of the 14 and 16-pin TTL chips, just like how IBM did it. In fact, it could be very very close to the IBM Printer Adapter (circuit diagram [here]). You could work back from the pins on your card's parallel port connector.
 
I had a look a couple on eBay - they aren't quite the same as mine as they don't have a parallel port (unless I missed the one you saw). Mine has both a DB9M serial and a DB15F parallel port on the backplane. Easiest way to identify mine is that it has the battery near the center of the board at the top; not near the metal backplane.

Out of curiosity could you post up the item ID?

I think I am in trouble though - There is a 40pin DIP which has the words "Persyst Parallel Port (C)". I'm guessing this takes the place of the discrete logic that IBM used :(

On another note the card refused to show the system it's extra RAM on bootup today. I think it was me playing around with the dipswitches as when I worked them back and forth again it found the full 640K. Not keen on losing that part of the functionality!
 
That doesn't sound too happy for the situation. The Persyst custom IC is almost certainly unobtanium if it requires replacement. I suppose you can see if there's any external address-decoding circuitry, but with 40 pins, I suspect that that's also in the chip.
 
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