undefined | Better HN

0 pointsdeater2y ago0 comments

It's likely it's 3 bytes of BCD (binary coded decimal). It's a handy way of storing things like scores, especially on 6502 processors which have built-in BCD handling support.

0 comments

hcs2y ago

No BCD support on the specific chip used in the NES, though.

tom_2y ago

Looks like it might be doing the bcd by hand. See, e.g., L93C7 (and following code) in the disassembly here: https://github.com/CelestialAmber/TetrisNESDisasm

j / k navigate · click thread line to collapse

0 comments

hcs2y ago

No BCD support on the specific chip used in the NES, though.

tom_2y ago

Looks like it might be doing the bcd by hand. See, e.g., L93C7 (and following code) in the disassembly here: https://github.com/CelestialAmber/TetrisNESDisasm

j / k navigate · click thread line to collapse