The Watchman Clock

This project began with my desire to build and play with a part of computer history that I skipped: CP/M.

In the early 1970's I designed and built my own computer, based upon the Intel 8008. My 8008 was operated by entering programs into memory from the paddle switches on the front panel.

I did write a small monitor program that would communicate with an ASCII keyboard and TV display, but that was about the extent of what I did. During the three years I spent wire wrapping and soldering my 8008, more functional computers were becoming commercially available at reasonable prices.

Being newly married and strapped for cash the next computer I bought was a Sinclair ZX81 in kit form. The ZX81 was a pretty cool little computer that natively ran BASIC, but had no operating system. BASIC was a no brainer for me after spending hundreds of hours up at the University of Utah playing with the Univac 1108 during my high school days.

Amazingly enough I found a company that sold a floppy disk controller that could be connected to the ZX81. I bought one and had dual floppy drives on my little ZX81! By the time I had learned just about everything I could by tinkering and programming the ZX81, the IBM PC had emerged.

My first step into the "PC" world was when I acquired an AT&T 6300 running MS DOS. From my humble beginnings with the 8008 the 6300 seems like a supercomputer!

For the price of four hundred dollars, I added a 10 Megabyte hardcard. Back then 10 Megs could just about hold all the PC software that I could get my hands on.

I also jumped off BASIC and started playing with Borland Turbo C. Over the past few years, I've wanted to build a little computer around either an 8080 or a Z80. At the time I built my 8008 the Intel 8080 was a several hundred dollar chip. Building around the 8008 was cheaper, but it ultimately limited my software options so I never crossed the bridge into CP/M land.

Fortunately for me 8080's and Z80's are still abundant as well as CP/M and application software.