When we left off I was talking about my experiences circa 1980. I had been writing Computer Aided Instruction (CAI) for the Army in BASIC. In particular, I was writing code for the Commodore Pet. It ran a particularly nice version of Microsoft BASIC, complete with support for both audio cassette storage and disk drives connected via the IEEE-488 GPIB interface standard.
Personal Computers of this era rarely had hard drives. The hard drives made developing software for the Pet relatively nice. It was while working there that I discovered that it was possible to write self modifying code on the Pet. That was, to my mind any way, a necessary, if not entirely sufficient, requisite for creating Artificial Intelligence.
During a Christmas leave we went home to Murphysboro, Illinois to visit my parents. My dad was a high school teacher and was negotiating the teacher’s salaries for the next school year. He had access to a Radio Shack TRS-80. I wrote a BASIC program that was essentially an early forerunner of a spread sheet to allow him to analyze the effect of salary adjustments on the overall cost of a given proposal. He could run two or three scenarios in the time that it took the school board to analyze one. I was proud of my impromptu hack.
After I got out of the Army, I went to work for a little company in Birmingham that specialized in selling personal computers to small businesses. They were particularly appreciative of my ability to go back and forth between building and troubleshooting hardware and writing software.
My big achievement there was a program that allowed a person with a blueprint of a sheet metal part to describe the part to the computer so that the computer could generate a paper tape to control the machine that automatically punch out the part. The paper tape was called a Numerical Control (or NC) tape. I called my program an NC Compiler. I had to write an assembly language driver to control the paper tape punch that was hooked up to the computer.
It is important to say that I wasn’t learning how to program in a vacuum. For my entire four years in the army and for years afterwards I subscribed to Byte magazine. Byte magazine was completely devoted to personal computer hardware and software. They published schematics of hardware, and listings of software. Every August the published their annual computer language special issue in which they featured a different computer language every year.
Byte is where I learned about Pascal, Lisp, Smalltalk, Forth, Modula 2, Ada, Prolog, and other languages that I don’t even remember off the top of my head. They also published reviews of the various personal computer hardware and software products. It was the only magazine that I had ever subscribed to that I read the advertising as diligently as I read the articles.
There were other computer magazines that were influential like Kilobaud, and Dr. Dobb’s but Byte was the best of the lot. I wonder how kids today learn about computers but then I remember that they have something that we didn’t. They have the internet. If you want to learn something about programming today you have your choice of articles, books, or even videos telling you how it’s done. For that matter, you have the complete back catalog of Byte magazine and Popular Electronics at your finger tips. Of course, they are a bit out dated now. The are interesting from a historical perspective I guess.
When I left the small startup in Birmingham they still owed me several months pay. I finally was able to negotiated a swap for some flaky computer hardware in lieu of the back wages that I had little hope of ever seeing. Subsequently, I spent many a frustrating hour investigating the operating system of the little computer by translating the numerical operation codes back to the assembly code mnemonics so that I could analyze them, a process called disassembly.
It was about this time that I decided to go back to college and finish my bachelor’s degree. In the next installment I will talk about the languages that I was learning, and some of my experiences working for Intergraph.
Sweet dreams, don’t forget to tell the ones you love that you love them, and most important of all, be kind.