Computing from the Old Days, brought back to life

[Joost Buijs]

My first computer was a Heathkit H8 with 16 kB memory and 2 cassette decks. On this machine I developed my first chess-program, written in 8080 assembler. I still remember it playing it's first moves in januari 1978.

After this I also got a Heathkit H89. At that time I was working for Heath in the Netherlands, this enabled me to get these machines at first hand.

[Don]

In Sinclair and Commodore computers there were a way to code in assembly using BASIC code (via Poke), maybe even the Altair has something similar? I think that the Drago sources can help you, if you don't want to code in BASIC. They are 8086 Intel assembly, i don't know if you can easly port that code to 8080 CPU but that project could be interesting.

The altair had no operating system. You used a cassette tape via a modem to load the basic interpreter, or whatever you wanted. It was a BAREBONES system...

To boot the interpreter from tape, you got to flip front panel switches for about 10 minutes to load the binary instructions by hand that would then read in the real loader program from cassette which would then read in the interpreter...

Lots of fun. I built one myself... The modem / cassette interface was a royal pain in the ass, as it was sensitive to volume level among other things...

I lost a disk once in a DEC system and had to key in the boot loader from a hex keypad and toggle switches - a small program that provided a way to read from the tapes so that I could restore the disk. Same exact concept. I was in a panic and had to dig through manuals to figure this out (and find the boot-loader program) as important company data was on the disks and losing it was my fault! I never told anyone what had happened until now.

[sje]

Some thoughts on a proposed assembly language chess program for an Intel 8080 CPU:

1) The target machine, a Briel Computers Altair Micro 8800 has 32 KB RAM, more than the typical enthusiast machines of the Old Days which usually had 4 KB to 16 KB RAM.

2) Eight bytes for a move: from/to squares, from/to men, flags, more flags, and a 16 bit centipawn score.

3) A move has four flags for SAN encoding; a move can be encoded into SAN without having the board present.

4) A move has three flag bits to cover regular/ep/castling/promotion status (eight cases).

5) A move has nine bits used (or reserved) for other flags.

6) The moves are generated and placed on a global stack which holds one leg of the search tree; 512 moves fit into 4 KB memory.

7) The search may go to 16 (maybe 32) ply; there is a ply indexed vector which holds data for each ply.

8) The search is not recursive; all search parameters have explicit storage and are not stacked.

9) Communication is done via the serial port, which may be emulated.

10) There are no assumptions about any file system or operating system.

[sje]

Heathkit H89: http://oldcomputers.net/heathkit-h89.html

At the time the H89 was introduced, I considered buying one. But it was fairly expensive and there were some concern that the floppy drive was unreliable because of its proximity to the CRT electronics.

[jdart]

I bought one because at the time it was one of the microcomputers with a 80x24 character display (that was a lot at the time!). But heat was a problem inside the case, especially if you started modifying it with some 3rd-party add ons. I had a RAM disk installed and a couple other goodies and then it was prone to overheating.

There is one of these in the Computer History Museum in Santa Clara, along with a lot of other neat things.

--Jon

[sje]

Heathkit tried to make a comeback last year but went out of business this year.

http://en.wikipedia.org/wiki/Heathkit

There was just too much overhead in the electronics kit business. The same overhead killed the S-100 bus systems in the late 1970s, and the Apple II bus systems by the late 1980s.

I'll guess that most people who buy a computer today never open it, not even to add memory.

[jdart]

I loved Heathkits, I was a big electronics hobbyist at the time (also doing a lot of homebrew projects). I'm mostly a software guy now. I still do some custom computer builds, but that is not as challenging or educational as building everything up from the component level.

--Jon

[stegemma]

...
To boot the interpreter from tape, you got to flip front panel switches for about 10 minutes to load the binary instructions by hand that would then read in the real loader program from cassette which would then read in the interpreter...

Interesting system.. have you never thinked about to build something like a carillon, just to automatically move up and down all the switches in the right sequence?

My dream are always been to write a chess program for the ZX81 with 1Kb RAM. I know that this program was already written but still it remains one of my dream. Maybe sometime i can find the time to try...

[Joost Buijs]

I loved Heathkits, I was a big electronics hobbyist at the time (also doing a lot of homebrew projects). I'm mostly a software guy now. I still do some custom computer builds, but that is not as challenging or educational as building everything up from the component level.
--Jon

It was the same here. In 1966 I started with electronics and somewhat later I became interested in amateur radio. Somewhere in the eighties I switched completely to computers and programming. I did a lot of homebrew stuff. At a certain point I even designed and build my own micro computer. Another project I did was a hardware move generator and tree search for Reversi (Othello). Unfortunately this was not very successful because by the time the project was finished it was not faster than what you could do with a (at that time modern) PC.

[sje]

Got it hooked up to a monitor and a keyboard. No cassette drive for storing programs; at present BASIC and other programs are loaded from an SD card.

Are you old enough to remember a boot screen like this?