Building my first computer!


Ok, so first was an Apple II+. This project was the first computer I ever designed and built chips up. Ironically it was based on a 68K processor and was basically a 1984 128K Macintosh, albeit one with much simpler ROMs.

Fall quarter of 98 I took EE478. It is the Electrical Engineering departments Capstone digital design course. It is the course tries to identify and fill in any holes that graduating EEs may have. It tries to do this through a series of rather large labs and one final baloon design project at the end of the course.

My partner, Dave Hobe, and I chose to build a 68K-based microcomputer. It t anything fancy, just some RAM, some ROM, buss-driving chips, and some home rolled memory management hardware. The kicker turned out not to be designing it at all but getting the thing up and running. Lets just say wire wrapping is not my friend. Still, 17 years later this project is still a personal favorite.

Since the design had to be wire wrapped we broke it across multiple boards. Here you can see the design folded open. The top layer was RAM and ROM, and the lower board housed the processor, and several eeproms that contained the memory encoding and decoding logic.

To avoid the massive number of wires turning into a s nest I braided the nibbles (every four wires) into bundles and then braided those bundles together. Mixed in with bundles of nibbles I braided in ground wires. It t make up for the lack of a ground plane, but it helped.

Here is a picture of my partner Dave Haube, Prof Peckol, the project and myself.