mirror of
https://github.com/deater/dos33fsprogs.git
synced 2024-07-04 08:29:30 +00:00
18 lines
666 B
Plaintext
18 lines
666 B
Plaintext
Cometsong
|
|
-
|
|
3-channel Mockingboard music with Lo-res graphics
|
|
256-byte Intro for Apple II, Lovebyte 2022
|
|
by Deater / dSr
|
|
|
|
Fitting Mockingboard music in 256B was a challenge.
|
|
Note: only plays music out the left stereo channel.
|
|
Thanks to mA2E for the music.
|
|
Thanks to qkumba for optimization help.
|
|
|
|
This code does a lot of tricky things. It loads into the zero page
|
|
(which makes memory use less) but the music data overflows into
|
|
the low half of the stack (at $100 on 6502). The rest of the code
|
|
avoids the use of the stack, so we can use the "PLA" (pull stack
|
|
to accumulator) instruction to do an auto-increment load through
|
|
the music. This trick saved 15+ bytes.
|