[cjfd]

When I was a teenager, I read a book about assembly language for the commodore and implemented the game of life in a really simple way. I just used the text screen. To switch on a cell, I would put an asterisk ('*') in it. Then I could run my machine code program and it would evolve according to the rules of the game of life.

[abcd_f]

And who didn't do that! :)

You could also 4x the resolution by using half- and quarter-block characters from the top half of the ASCII table (or it'd be the PETSCII one i C64 case).

[lproven]

> And who didn't do that! :)

Exactly. It's even how I taught myself extremely basic Pascal -- getting my BASIC Life program running in Pascal. With asterisks.

A taught a friend at uni, who was a much better programmer than me, how the algorithm worked. He did a pixel-by-pixel version in machine code, but it was a bit slow on a ZX Spectrum.

So he did exactly the quarter-character-cell version you describe. I wrote the editor in BASIC, and he wrote a machine-code routine that kicked in when told and ran the generations. For extra fun he emitted some of the intermediate state to the border, so the border flashed stripes of colour as it calculated, so you could see it "thinking". Handy for static patterns -- you could see it hadn't crashed.

I've been considering doing a quarter-cell Mandelbrot for about 30Y now. Never got round to it yet.

[jerf]

The answer to a lot of "wow, how did the 8-bit machine pull that off? it seems like that would eat a lot of RAM" is that the framebuffer is the data storage. You were literally looking at the primary data store itself, because when a full-resolution framebuffer was 1/4th your addressable RAM (and slightly more than that for your actual RAM since you couldn't ever quite use all 64KB no matter how you mapped it), you need to get the most bang for the buck out of that RAM usage as you can.

[tempaccount5050]

Ha, I remember doing this with my Apple //. I forget what I was doing, but realized if I could set a pixel and later get what color was drawn at that location I could use it as a big array. Didn't know about peek/poke yet. One of those core "computers are magic" memories.

[alnwlsn]

When I got into retrocomputing a few years ago, I also did this. Works great with TRS-80 semigraphic characters. First, I wrote it in C with a Z80 c compiler. The, I wrote it again in assembly and it was much faster! Amazing!