The Osborne 1

The Osborne 1 was a portable CP/M computer with a Z-80 processor. It looked like a portable sewing machine. You tip it on its side and undo the latches and the end would come off revealing a keyboard which was attached to the rest of the machine by a wide ribbon cable. Removing the keyboard revealed two large floppy drives, a tiny 5 inch screen, cubbies for floppy disks, and a bunch of ports. We would plug the RS-232 cable from the paper punch into one of the ports.

The 5 inch screen could only display 52 characters wide, but it could scroll. You had to have a tolerance for reading very small type to use this machine. I was okay with it, but today I probably wouldn't enjoy it.

Aside from editing CNC programs, we also had MBASIC on these machines and so we could do a little programming to help us with our work. Bob knew how to write in BASIC and he had written a few things. For example there was a program for spitting out a simple routing program for a rectangular board. You just punch in the size of the board and it would generate a file. Anything more complex than that required manual coding.

One problem we had with the Osborne 1 machines we had was that the keyboard bezel was metal and it wasn't grounded well. If you walked up to the computer and touched the keyboard it wasn't unusual to discharge some static electricity and reset the computer, losing whatever work you were doing.

6502 Assembly Language

My brother Ernie is a little more than a year than I. He was ahead of me in the programming department when we were kids, and my first exposure to assembly language was through a book he had on Z-80 assembly language. I never did have an opportunity to try Z-80 assembly, but when I had my VIC-20 I decided to try 6502 assembly language. I didn't find machine language hard at all to grasp because it seemed very similar to the language used to program calculators, especially the HP-67.

I was a regular reader of COMPUTE! magazine, and in one issue they included source code in BASIC for a 6502 machine code monitor. This was a far cry from an assembler, but it was better than nothing. I wanted to try speeding up a side-scrolling video game, so I decided it made sense to write an assembly language routine to move characters from the right to the left by one character. This is how video game graphics were done on the VIC-20. You could program up to sixty four 8x8 pixel custom characters, and you put these on the screen for some crude graphics.

So, since I didn't have an assembler I needed to be my own assembler. The VIC-20 Programmers Reference Guide included all the information I needed to write my first assembly language program. Once I had the code written, I translated the assembly language instructions into machine code. On the 6502 the instructions are in the form of hexadecimal numbers. I typed these into the machine language monitor to try them out. I don't remember if I got this to work the first time.

When using machine code in BASIC on the VIC-20, you would usually convert the hexadecimal numbers into decimal and then put them in a DATA statement. Then READ the numbers and POKE then into memory and call the routine with the SYS statement.

The great thing about the VIC-20 is that anyone can learn to do these things. It's fun!

Stop reading this right now. Go to ebay.com and buy a VIC-20. Go to amazon.com and buy a copy of the VIC-20 Programmers Reference. Try it yourself! Seriously!

The Apple II+

My job with Mr. Alessi started out with a software project he called Forecaster-Buy. The idea was to create a trend following inventory management system for distributors and manufacturers so that overstocking was a thing of the past. The computer we did all our initial development was:

An Apple II+ with 48K RAM and Applesoft BASIC in ROM
Two 143K Apple Disk II floppy drives
An Epson MX-100 dot matrix printer
Later we added a Microsoft Z-80 Softcard but didn't do much with it

I learned so much about programming with Mr. Alessi. We worked in the basement. There was a small room at the bottom of the basement stairs where the computer was kept, and in the larger basement space there was a TV and some chairs. We would talk about the software (and politics) and I would go into room and write software. Mr. Alessi would come in and ask me how I was doing. He'd make suggestions to which I would sometimes respond "That's impossible!" Of course it wasn't impossible, but if I didn't know how to do it, that is what I sometimes said. Then we'd talk and I'd think it over and come up with some sort of code to do the previously impossible.

Working with Mr. Alessi was a great experience. He was smart enough to know what sort of software to create. He'd bring me endless coffee and cookies. On Saturdays he would make me breakfast. He made very nice scrambled eggs. His two sons Tom and Michael were a little older than me and they'd always be around. I remember I used to play with them (and with all the other kids around the block) up at the park at the end of my street; kickball, pickle, keepaway, capture the flag, and hide and seek with the whole neighborhood as our hiding place. :-)

Yeah, working with Mr. Alessi was a great opportunity. It didn't pay much, but I learned a ton!