Comment by vidarh | Hacker News Reader

Comment by vidarh | Hacker News Reader

The most amazing thing about this to me is the description of the internals of Robotron... Given a lot of the 8-bit machine code I've read it's simply astonishing to hear about a game of that era being so structured rather than the more typical approach of the day of hardcoding data all over the place (some games even used the on screen life counter as the actual "variable" holding the number of lives left, often full of bugs like not overflow checking the values) and using a basic event loop hanging off the irq. A lot of the time it was seen as necessary in order to fit everything in the small amount of memory, and so even on larger machines like the Amiga a lot of programmers kept manually laying out data structures for many years...

Compare the recently released Prince of Persia code to that description, for example. I found the Prince of Persia code very clean and readable for the period when I read it, but still relatively typical of the style of 80's 8-bit machine code programs even if it looks like it avoided the dirtiest tricks.

A game from that era using dynamic memory allocation, multi-tasking and an object oriented structure just sounds totally alien. Even Amiga games, running on a system with substantially more memory, and on an OS with substantial built in support for it mostly, - with some honourable exceptions - just disabled the multi-tasking entirely and often hung everything off a loop tied to an interrupt handler or at most an interrupt handler and a separate "main" thread.

That's a Eugene Jarvis and Larry DeMar game. He also co-wrote Defender, Smash TV, and other classics with DeMar. Eugene now teaches at DePaul in Chicago.

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

Jarvis also owns/runs Raw Thrills, a game design company outside of Chicago.

http://www.rawthrills.com

DeMar owns/runs Leading Edge Design, a slot machine design company. He also cofounded Spooky Cool Labs, a social game design firm. Spooky Cool was sold to Zynga late last month.

http://www.spookycool.com

The 6809 is a very nice 8-bit CPU, designed with the intention of using higher level languages---it could generate position independent code, had four general purpose index registers (all 16-bit, one was also the system stack register), two 8-bit accumulators that could be used as one 16-bit accumulator, and had some rather advanced addressing modes.

As a kid, I used to adore the 6502. Now, after many years, having used 68k and MIPS assembler, I feel that the 6502 is just awkward to code in. Everything you do is so hardcoded and specialized for the task.

I wish the C64 had used a 6809 or z80 instead.

The 68xx range wasn't viable for low cost machines until it was too late and Commodore was already deeply invested (as in, it owned MOS).

Keep in mind that the entire reason for being for the 6502 was that Chuck Peddle had tried (and repeatedly failed) to get Motorola to accept the idea of pushing a low cost design. At the time the 6501/6502 was introduced MOS charged $20 per CPU while Motorola was charging $175 for 6801's. Motorola dropped their price to $69 near instantly, but that was still a substantial percentage of the cost for a typical low end machine.

On a machine with more memory it might have mattered, but for a machine constrained to 64KB, the 6502 instruction set was easy enough to work with - it's not like you could afford to use a large stack most of the time anyway, for example.

One thing that I think that is important to understand is that these machines, and this code, is still out there, working. People are still playing these games (MAME) and the emulation scene that has arisen due to the fanboix fervour has really pushed a lot of the gems into the 21st century with new life and vigor. The "automatic game player"-coded-in-z80, i.e. hardware playing hardware, is a real hoot!

And last but not least, consider this: people are still writing amazing software for the older architectures, using modern principles, and learning astonishing new things about the "antique hardware", to boot! In my particular nook I have witnessed the Oric-1/Atmos machines (http://oric.org), typically considered a fairly "grotty" 8bit machine of the 80's, never enough decent software, died early .. yet now come to new life with the discovery of never-considered color-modes and graphics capabilities by some of the modern scenes very elite hackers, turning their eyes to the "old" machines and producing new hits!

I think a lesson in all of this is that the old machines still contain a lot of power. The robotron code could probably be refactored into something else, easily enough, if there was some intention behind doing it. There are a lot of 6809's out there, still, presumably in landfill its true, but nevertheless one could do worse than to re-discover old machines in the modern era, were one to want to sharpen ones skills ..

In Commodore circles the Oric machines were often derisively called "doorstops" as that was the only thing we considered them good for as kids. Of course this was without ever having used one, and was reatively mild compared to the Commodore fanboy hatred of Atari. Much less tried to exploit it to its limits like with e.g. the C64 which is in a similar situation in terms of new discoveries despite how well it was mapped out by the late 80's (I remember finally getting my hand on a copy of a hand written diagram of exactly how many bus cycles the graphics chip "stole" from the CPU under what circumstances - essential to many demo effects that even many Commodore designers insisted were impossible until they were demonstrated...)

I'm not sure about 6809's, but the very similar MOS/WDC 6502 derivatives is still manufactured by Western Design Centre, founded by Bill Mensch (the co-designer of the 6502 together with Chuck Peddle, who was on the 6800 design team at Motorola for some time, though he joined after the main 6800 design was done): http://www.wdesignc.com/wdc/

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