Last week I began to disassemble the 4KB, 1979 pinball game for the Astrocade called Bally Pin. The game looks like this:
Today I've reached a point where it's worth sharing. You can download it here:
Most of the ROM can be seen in Z80 mnemonics now. Sure, it's hard to follow, but it beats reading hexadecimal!
This code can be assembled using the Zmac assembler and the Home Video Game Library (HVGLIB.H), which are both available here:
I became interested in disassembling this game in May of 2016 when we played Bally Pin in the Astrocade High Score Club, here:
The game's manual looks like this:
The game cartridge looks like this:
I'm learning to use the MAME debugger a little better, which makes disassembling the game go a bit faster. Most of the ROM has been disassembled, but I have not started to follow the game's logic yet. Although, to a certain extent that isn't true, for it's impossible to disassemble a game without following the logic a little bit.
Today I disassembled the music "scores" used by the on-board ROM's music routines. By "score" and music, we're actually talking about sound effects. I hope that tomorrow I can start looking into the graphics of the game. I'd also like to see if I can follow how the game gets laid out.
If possible, I'd like to add a few well-placed pixels so that the ball doesn't drain. It would be cheating, sure, but it would make disassembling the game go faster, as I have been playing the game without mixed results. If I can't prevent the ball from draining, then maybe I can at least add more default balls when the game begins.
As progress continues, I'll post the disassembled source code to BallyAlley.com and mention it here.