Some googling tells me it's assembly, but it's nothing I recognize...

Thanks! you beat me to my edit.. ;-)

Looks like a MOS Tech 6502? Seems pretty similar to a Zilog Z80. 8 bit processor with a 16-bit PC, though seemingly without the 16-bit paired 8-bit registers.

Machines from when assembly was still fun.

MOS Technology 6502B @ 1.79 MHz (NTSC version) @ 1.77 MHz (PAL version)

It's the code for the Atari 800 version, I believe, so that's the processor.

Some info on the assembly language for the 6502b http://en.wikibooks.org/wiki/6502_Assembly

It is 6502.

(I'm not sure the 6502 counts as particularly much like a Z80?!)

Agreed, I had a Z80 card in my Apple II and they are very different. I found assembly on the 6502 a little easier but the Z80 allowed me to run CP/M and that opened the door to a tone of SW.

Perhaps not, I'm mostly just familiar with the Z80 though so I might just be seeing what is familiar to me. ;)

It is about as Z80 as an ARM Cortex is a Pentium M.

back then we really only had Assembly as an option for games. It was a speed issue more than anything else.

Also code space. The cartridges I wrote typically over-filled the code space by a factor of 25 percent, whereupon you crunched.

Usually you wound up with a handful of bytes free. One cartridge I did had 6 bytes left, and another one had less than 20 and I was trying to think of something cool I could do with 20 bytes.