PoC or GTFO, Volume 3

Introducing Gumboot

Gumboot is a fast bootloader and full read/write RWTS. It fits in four sectors on track 0, including a boot sector. It uses only six pages of memory for all its code, data, and scratch space. It uses no zero page addresses after boot. It can start the game from a cold boot in three seconds. That’s twice as fast as the original disk.

qkumba wrote it from scratch, because of course he did. I, um, mostly just cheered.

After boot-time initialization, Gumboot is dead simple and always ready to use:

entry	command	parameters
$BD00	read	A = first track Y = first page X = sector count
$BE00	write	A = sector Y = page
$BF00	seek	A = track

That’s it. It’s so small, there’s $80 unused bytes at $BF80. You could fit a cute ...