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The greatest program ever written

By codemonkey_uk in Op-Ed
Fri Aug 10, 2001 at 01:13:48 PM EST
Tags: Technology (all tags)

I'm a programmer. I write games. Games programmers get a lot of respect, but none of them, not me, not Carmak, and not Abrash. None of them deserve the honour which I want to bestow on David Horne. This is because David Horne wrote the greatest program ever written: 1k chess on the ZX81.

David Horne is not an urban myth. David Horne achieved what many would even now consider impossible. He wrote a chess game, with AI, that ran on a poorly documented, buggy machine that contained only 1k of memory.
The Sinclar ZX81.
Think about that amount of memory for a moment. 1 kilobyte. 1024 bytes. Can you write down the rules of chess in less than one thousand characters? That's a tricky task in itself. Fire up you favourite compiler, and build a minimal application. I'm guessing that its more than 1k in size, and it doesn't do anything yet.
But wait a second. 1k was the capacity of the machine. How much was actually available? The answer, as you will find if you follow the link at the end of the article, is a meagre six hundred and seventy two bytes! This article takes up more space than that.
And it had AI. Not very tough AI mind you, but AI none the less. So not only could is display the board, verify the your moves according to the rules, and detect a win or a draw, but it could select moves for itself and play them.
All this and more. He not only conceived and executed the idea that a game of chess could be packed into so few bytes, but he published the source code, along with a detailed explanation of how it was done in the February 1983 issue of `Your Computer' magazine. This article is essential reading, a trip down memory lane for those of us old enough to remember those furious, exciting 8 bit days, when the limitations defined the experience of programming, and an important piece of history for those brave young hackers who take for granted the luxuries of life, like compilers, swap space, and keyboards that click.
So, David Horne, if your out there - this is for you. I, and I'm sure, my fellow programmers, bestow upon you this honour: You, sir, created The Greatest Program Ever Written.

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The greatest program ever written | 25 comments (22 topical, 3 editorial, 0 hidden)

1k is plenty! (2.75 / 4) (#1)
by pallex on Fri Aug 10, 2001 at 12:25:54 PM EST

Enough to run a power station, apparantly. (Or did you need the 16k ram pack for that?)

Power station by fluffy grue, 08/10/2001 06:25:00 PM EST (4.00 / 1)

Yes by marimba, 08/11/2001 12:34:43 AM EST (4.50 / 2)

Atari 2600 Chess (3.33 / 3) (#2)
by IntlHarvester on Fri Aug 10, 2001 at 12:32:56 PM EST

OK, it had a 4K ROM, but still a pretty amazing accomplishment considering that the machine only had 64 bytes (or whatever) of RAM. The AI is actually fairly decent too, or so I hear from chess players.

I'm sure there will be plenty of other examples of 1K chess from the old minicomputer days.

cartridge systems by codemonkey_uk, 08/13/2001 04:37:27 AM EST (none / 0)

Sorry, 128 bytes by IntlHarvester, 08/14/2001 12:40:46 AM EST (5.00 / 1)

Clever stuff by codemonkey_uk, 08/14/2001 04:09:35 AM EST (none / 0)

RAM in the VCS by davidduncanscott, 08/16/2001 05:31:39 PM EST (none / 0)

Assembly (3.33 / 6) (#5)
by ucblockhead on Fri Aug 10, 2001 at 01:01:44 PM EST

It is amazing what you can do out of necessity. It is also amazing how little memory you need when you give up the bloat of languages and OS and just code at the raw metal. It is unfortunate that younger programmers don't get the experience of trying to cram stuff into limited program space.

I also find it amusing that in these days of games delivered on multiple cds, some of my favorite games of all time fit on 140k floppies, with room left over.

-----------------------
This is k5. We're all tools - duxup

cs.nmsu by fluffy grue, 08/10/2001 06:22:24 PM EST (4.00 / 1)

RAM-pack wobble, anyone? (3.50 / 2) (#7)
by projectzero on Fri Aug 10, 2001 at 03:59:02 PM EST

The ZX81 had an extremely dodgy edge-connector expansion port on the back - a hallmark of all Sinclair machines - which was only secured by the pressure of the female connector pressing down on it. People who went out and bought the (extremely expensive) 16K RAM expansion packs offered by various vendors soon found out exactly how crap the connector was. Hit a key too hard typing in your latest opus (like, say, 1K Chess from Your Computer, which I may still have a copy of somewhere if I look deeply enough into my cupboards), or cause the machine to otherwise move about, and you were very likely to suffer from RAM-pack wobble; one line of the expansion port disconnected was all it took to reset the machine - and lose your program - entirely.

It was the BSOD of its day :-)

Seriously, though - all programmers should have to try doing something useful with a ZX81 or Spectrum or some other memory-limited system. It teaches you to think your way around problems. Too many lazy programmers these days just use brute force or CPU cycles to get over a hump they could have coded elegantly around. Makes me ashamed to admit to coding in VB...

RAM-pack wobble, anyone?: Solved by nickrud, 08/11/2001 01:14:09 AM EST (3.00 / 2)
Premature optimization is the root of all evil by afeldspar, 08/11/2001 11:28:17 AM EST (4.33 / 3)

The thing to remember ... by codemonkey_uk, 08/13/2001 04:40:42 AM EST (none / 0)

Bah! (3.33 / 3) (#8)
by cyberdruid on Fri Aug 10, 2001 at 04:35:11 PM EST

What kind of random rant is this?! Many people wrote 1k chess-programs. There were even competitions for them!
To my knowledge this Horne-dude was not the first to do it either (although I did not have the energy to research the matter). For example, in 1976, a Canadian named Peter Jennings wrote a program called Microchess 1.0; it ran on an obscure microcomputer (the Kim 1), which contained a 6502 CPU, no ROM, and 1K of RAM. The program even played decent chess.
By the way, the greatest programmer ever was probably Newton or perhaps Eratosthenes. They thought up algorithms just for the theoretical pleasure. Totally impractical in a time without Turing-like automatons, but used hundreds of year later.

/Mr. Cyberdruid

Cite reference by codemonkey_uk, 08/13/2001 04:24:06 AM EST (none / 0)

Consider some of the programs... (3.50 / 2) (#9)
by jd on Fri Aug 10, 2001 at 04:37:37 PM EST

On the ZX80, the infamous predecessor to the ZX81. This had something like 256 bytes available, and yet some amazing programs were written for it.

Going back a LONG way, the first-ever stored program was a program for calculating the highest common factor of two numbers. IIRC, it occupied a grand total of 12 32-bit words.

A little bit further forward in time, now, and you reach =THE= two games that defined the 1980s - ELITE, and REVS. The first was a space trading and combat simulator, supporting 32 tradable items, 2 types of solar system, over 100 spaceships, 4096 systems, 2 missions, some stunning graphics (for the time), an economics engine, a political engine, a decent AI, medium-resolution graphics (in two different resolutions at the same time), =and= a very nice logo. The whole thing fit onto 7K of RAM and a 100K floppy. Or, it you wanted to cut out the missions, half the spaceships, and half the systems, you were left with something that just took that 7K.

REVS, on the other hand, was a Formula 3 simulator, with OK graphics. The main attraction of REVS was the quality of the simulation. The aerodynamics and the car's behaviour were very respectable. Far better than any other program of the time, and (IMHO) respectable in comparison to any program today. This program was a little larger, weighing in at something like 17K, but name a programmer today who could even DREAM of coding something that compact!

That's easy by Rainy, 08/10/2001 04:50:01 PM EST (2.00 / 2)

Maybe you should try it by Tatarigami, 08/11/2001 05:04:16 AM EST (3.66 / 3)

I was kidding. by Rainy, 08/11/2001 02:24:41 PM EST (3.00 / 3)

Buggy? (none / 0) (#23)
by gordonjcp on Thu Aug 16, 2001 at 10:13:12 AM EST

a poorly documented, buggy machine

Gzzht? Whh? (other noises of incoherent indignation) WTF?
Come on, the ZX81 was rock solid. I still have my original one, along with a couple of others. Read the article, Chess in 1k!! Thus no ram pack, hence no infamous ram pack wobble.
And poorly documented? The user manual had 4 pages or so describing the internal system variables, and what you could poke into them. All 20-odd variables fully documented!

[splutter, rage...]

Give a man a fish, and he'll eat for a day. Teach a man to fish, and he'll bore you rigid with fishing stories for the rest of your life.

Yes. Buggy. by codemonkey_uk, 10/02/2001 09:49:17 AM EST (none / 0)

The greatest program ever written | 25 comments (22 topical, 3 editorial, 0 hidden)

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