One more try - Can you ID this S-100 Serial board?

On Thursday (10/01/2015 at 06:27PM -0500), drlegendre . wrote: This is where I'm holding onto my theory that it is a custom design for a specific purpose-- as I do not see the usual jumpers or DIP switches to set I/O or memory addresses. If it were a generic card built for general purpose use, it would almost certainly have DIP switches to set an I/O or memory address decode. On S-100 systems, you have both I/O and MEMORY space. Things like serial port cards were almost always in I/O space and were decoded within a 256 byte block. Different S-100 systems had their console or other I/O at different addresses and with different chips (8251, 6850, 2661 and other UARTs with internal register sets as well as TR1602, AY-3-1015 and similar "dumb" parts). Without any jumpers or switches to set the decode, you will have to reverse the design to figure out how they did it. It might be I/O mapped but it might be memory mapped since it was likely purpose built for a specific application. Along with this, you will probably not have operating system support that understands how to talk to this setup so you will need to modify a CP/M BIOS or other OS I/O support to understand how to talk to it. The AY-3-1015 UARTs are "dumb". Their framing format is decided by strapping inputs to the chip and then they present a byte-wide input register and output register and strobes to read or write those registers. This would likely be handled by buffers with enables to gate these paths onto the S-100 bus. I concur with Chuck that there were and are a lot of "MCT" companies. I just have a high confidence that the logo on Bill's board matches the logos I am familiar with for the local MCT here in town. Chris -- Chris Elmquist