george barone wrote:
Wow, what an amazing piece of work, how long did it take you to put it together? What did you actually program it to do? Fantastic
Thanks. Honestly, it was so long ago that I don't recall the time frame involved in getting it to that state. It started out similar to the simplified version shown in the
Popular Electronics picture. Then, I decided I wanted to fully decode and display the full address & data buses, add more memory, etc. So I designed circuitry to do that and wirewrapped the changes. Everything wasn't done all at once -- I'd add functionality when it occurred to me. As a guess, I'd say that it went from barebones to its final state as shown in the pictures in a year or so. The individual updates didn't take lone -- wirewrapping is very quick -- a few hours or a couple of days, at most. (assuming no wiring or design errors...)
Programs were loaded a byte-at-a-time, using a very sparse 'operating system' called
ETOPS, (
Elf
Toggle
Operating
System) which made it a little easier to enter data. Everything was straight machine code represented by hexadecimal digits set in the toggle switches. Once the program was entered, you had to specify the starting address in memory, press the "
Run" button and then start troubleshooting why it didn't do what you wanted it to do...
The most 'sophisticated' application I wrote for it was a telephone dialer, which was accomplished by hooking a relay across the phone line and having the computer pulse-dial a number by opening and closing the contacts the correct number of times for a given digit, using the phone company's pulse dialing specifications. Once a number was programmed in, it could dial faster than you could on a real telephone, but it took more time to enter the number into memory than it would to pick up a phone. It was just a programming exercise, really.
Tiny Basic was available for the
Elf, but I moved to the
Kim-1, which I could hook directly up to a
Teletype machine. So the Elf remained my only computer for a relatively short time -- a year or two, maybe.