Category Archives: RetroChallenge

I’ve created a Github repository for my PACE assembler and simulator, which together with some very incomplete support for National’s IMP-16 multi-chip processor, I call ns16.  It is released under the GPLv3.  This was all work done back in 2009 … Continue reading →

After quite a few hours with a continuity tester and magnifier, I have the PACER CPU card mostly figured out, and have drawn a schematic . I haven’t identified all of the passive component values, and there are probably other … Continue reading →

One of the things I’d like to accomplish in RC2015/01 is to get some non-trivial software running on the PACER. In addition to hardware restoration work, this will require building a memory expansion, because as supplied it only has 1Kx16 … Continue reading →

I’ve written about what I did with the PACER before the RetroChallenge, so henceforth I’ll describe what I’m doing for the RC. I’m starting with tracing out a schematic of the motherboard/backplane, including the power supply, the eleven edge connector … Continue reading →

I found some of my notes from August, so there are a few more details about the state of the machine, and preparations made at that time, particularly relating to the fuse holder and power supply.

In August 2014 I spent a few days evaluating the condition of the PACER as a candidate for a RetroChallenge project. I took it apart, did some cleaning, and preliminary study of the unregulated linear power supply. As received, one … Continue reading →

One of the first available 16-bit microcomputers was the PSE Pacer, introduced in 1976.  (NOT the contemporaneous AMC Pacer, though I knew someone who had one).  My Retrochallenge project is to restore and reverse-engineer the Pacer, and time permitting, write … Continue reading →

My RC2015/01 project is to reverse-engineer and restore a 16-bit microcomputer (not a minicomputer!) that was sold in 1976, and design and build a memory upgrade and serial interface for it. If there’s time left after that, I’ll try to … Continue reading →

My primary accomplishment for this RetroChallenge was making substantial improvements to my standalone floppy disk formatter program for the Quay 900. In the course of trying to find information about the Quay, I created a consolidated advertiser index for the … Continue reading →

Mostek published a great little Z80 reference card called the “Z80 Microcomputer System Micro-Reference Manual”.  In addition to the Z80 CPU, it covers the PIO, CTC, and SIO, but not the Z80 DMA.  Unfortunately it’s long out of print, so … Continue reading →