In 1981 I worked for a company called Nabu Manufacturing based in Ottawa. Nabu created an Internet precursor that was based on two-way cable networks. At Nabu I managed a department of two and we designed and created an S-100 compatible PC.
Together with Dave Wiens, my very capable assistant, we wrote the specification. Dave did the hardware development, and I wrote a CP/M-compatible operating system that booted off a cable modem and development tools for Nabu’s games programmers. Today I marvel at Dave’s patience, since I was only 25 years old and he was considerably older and so much more experienced than I. I learned so much from him!
Here are some pictures we took at the end of the project:
The Dolch logic analyzer was a joy to use. We could find bugs in real-time.
This is the board that Dave made – I learned a lot about SSI and MSI logic design from him.
Dave was usually a hard working guy. We got along really well.
This is what the development system looked like. We connected a Volker-Craig VT-100 clone to the serial port, and a TV to the NTSC output of the TI 9918 video chip. Notice the 8-inch floppy drives.
We used an extension board so we could attach probes to the S-100 card that we were working on. I think the Z80 chip ran at 1 MHz, and the S100 bus ran slower than that, so a six-inch extension on the bus didn't wreak the havok that this would cause with today’s clock speeds.
Tracking down a bug on the Dolch logic analyser often meant attaching probes to some chips and studying the rising and falling edges of the waveforms. We also decided where to put trim capacitors according to the voltage ‘bounce’ shown on the scope.