Incremental Blogger

A stroll down computer memory lane

A week or so back there was a blog chain forming around the topic "What was your first experience with computers?" Here's my contribution:

Somehow in 1976 I heard that my school allowed students to use their teletypes (connected to a PDP-11) after hours. So my brother and I did. We had no idea what we were doing. We wrote in BASIC. No one taught us to program. We taught ourselves by reading discarded print outs we found in garbage cans. For backup, we saved our programs on paper tape. It became a bit of a competition between my brother and I to see who could generate the longest tapes.

It's funny how some things stick out in my memory: This is where I discovered random numbers. My brother and I were writing baseball games at the time so we randomized everything. It was lots of fun. We moved that year, so the programming ended for a while.

My next hands-on experience with computers was my senior year in high school in 1978. Framingham North High School was offering a new shop class in micro-computers. So I took it. I didn't know the difference between a resistor and a capacitor, but as a group project we bread boarded an 8080 with 1K of 21L02 static RAM, 8K EEPROM (I think, or maybe 1K), 8 switches for input and 8 LEDs for output. It didn't do much until a student named Steve Rosenthal took home the 8080 manual for the weekend and came back with an EEPROM burned with a Tic-Tac-Toe program he wrote. It worked. The first time! Amazing—especially considering the fact that he had to burn the EEPROM by toggling switches by hand!

Inspired by our early success, a couple of us started building 8080 S-100 systems under the guidance of teacher Jim Pollard. My S-100 system is shown at right. I think much of what we were learning was coming from the Boston Computer Society, but I'm not sure. It had 8K RAM, 16K EEPROM, a black and white video controller, Kansas City cassette tape backup, front panel, and some glue circuitry.

Somehow we got a BASIC EEPROM. I wanted to know how it parsed and processed BASIC so I disassembled it--by hand. That's where I first saw the names Paul Allen and Bill Gates—in the copyright notice. (Drats. I'm pretty sure there was another name too. I can't remember right now and the papers are in storage.)

At the time, I lived and breathed Don Lancaster's TTL-Cookbook. Don lives here in Arizona now, still going strong.

I built a couple small Z-80 systems after that, but my real passion was with Robots. So I went back to school. I remember taking CS courses for the first time at Arizona State University. I had to relearn a lot. Things such as De Morgan's Theorem and hash tables were concepts I'd used, but never had names for. Now I had to. It took a lot of work to get back up to speed again. And I was happy when I could churn out a 500-line FORTRAN program.

Then I met Dr. Rich Madarasz. He was building a Robotic Wheelchair. And that's where I was first introduced to the IBM XT--in '84 I think. Our development machine was a 4.77MHz 8088 with 64K RAM and a 10MB drive. We wrote most everything using Lattice C. The Robot sported a 4.77MHz Compaq transportable strapped to its back and an AT&T 8 MHz speed demon as passenger.

I remember one extra-bright student that wrote the interrupt handlers for the optical encoders on the Robot, Len Quadracci. No one else in the group knew or figured out how to do it. He did. Len interviewed up at Microsoft's Hardware division in '86 (or '87). He didn't get the job, but even then it was obvious that Microsoft somehow was able to pick out the best. They just made a mistake in not hiring him. :-)

One other notable moment along the way: I remember when I first saw the schematics for the Apple II. It was in the fall of 1979 and I was blown away by its elegance and balance between hardware and software—particularly with its keyboard and video controllers. That was the beginning of my transition from the hardware world to the software world. Plus, I could see that it was a lot cheaper to experiment with software than hardware.

Jim Pollard, Don Lancaster, and Rich Madarasz all shared their knowledge. I learned a lot from them. And now I know that someone out there may be reading this blog right now, devouring my every word much like I did when I dug through the garbage cans looking for BASIC code.

Posted by Loren at June 12, 2003 06:12 PM