View Full Version : Unknown S-100 card - need help

May 5th, 2008, 09:08 AM
I too am rebuilding an Imsai 8080. I built several new ones in college (1977) and found one that needed some love. Everything is working and I have been scouring the web tubes for old S-100 cards.

I am currently trying to get my serial port to work. I am using my $4000 Mac Pro as a dumb terminal and have the Processor Technology SIO card. Not quite there yet with the basic communication, my RS232 memory is a bit rusty (now which one is the data set??)

I recently came across a S-100 card that has four serial ports on it. Professionally made, in excellent condition and absolutely no documentation. The only markings on this card are "C.E.P.C. 4-sio-2 Rev 2A"

I have been unable to figure out what the CEPC is. I cannot find any record of such a company and none of the S-100 archives out there have any reference to it or to a card referred to as 4-SIO-2.

Anyone remember anything about this thing?

Jeff Erwin

May 6th, 2008, 05:46 AM
Your best bet may be to use data sheets and make a block diagram with enough detail to make cables and set the address and most likely the interrupt jumpers/dip switches.

I assume that it has 2/4 UART chips and they would feed either a set of 1488/1489 or 75188/74189 chips for the RS232 in/out. I would start with the data sheet of the UART and an ohm meter and by looking at an example circuit that most data sheets have and compare that to your board to figure out the the in/out of the different RS232 connector pins.

On the S100 bus side should be common 7400 series chips (hopefully) for buffering and address selection.

Also looking at other SIO cards will help give you an idea how they work and help you figure your card out.

Hope this helps


May 6th, 2008, 08:10 PM
Please post some pics of the card, that show a high degree of detail. I have not heard of the card, but maybe I or someone more knowledgeable than I can identify by the jumpers and switches for clues as to what the card may have been specifically configured to do. There were a lot of SIO card manufacturers in the late 70's. Are there any PROMs on the card, or just SIO/PIO connector points?