Sound Hacking/Sega Consoles
Contents
Sega MegaDrive/Genesis sound hacks
Simple Triggers
These are simple memory triggers. Setting the respective bytes in 68000 or Z80 RAM will cause the game to immediately play a song or sound effect.
See BlastEm's page for instructions on how to use these in that emulator.
| Game | Sound Driver | Music Trigger + Comments |
|---|---|---|
| Bill's Tomato Game | Krisalis/Shaun Hollingworth | maincpu.w@FF900E = xxxx
|
| Chuck Rock | Krisalis/Shaun Hollingworth | maincpu.w@FF0014 = xxxx
|
| Sonic The Hedgehog | SMPS 68k | maincpu.b@FFF009 = xx
|
| Sonic The Hedgehog 2 | SMPS Z80 | genesis_snd_z80.b@1B88 = xx
|
| Sonic The Hedgehog 3 | SMPS Z80 | genesis_snd_z80.b@1C0A = xx
|
| Spider-Man vs. The Kingpin | unknown custom | play SFX: maincpu.b@FFE6EC = xx, values 00~31pause music: |
Advanced Hacks
This section contains ROM patches for playing songs/SFX, as well as hacking information like ROM/RAM offsets and sound driver RAM layouts.
Adventures of Rocky and Bullwinkle and Friends, The
ROM patch to play a certain song at the SEGA screen:
offset hex patch description 03C29E 05 A4 -> 00 02 ; ignore bad ROM checksum 04C0F7 03 -> xx ; where xx = sound IF 068B9C 6A -> 60 ; make it freeze on the SEGA screen
The PlaySong function is located at ROM offset 05618A.
Baby's Day Out
ROM patch to play a certain song at the SEGA screen:
offset hex bytes ASM code description 019FC4 41F9 00FF 0408 LEA $FF0408.L, A0 019FCA 4210 CLR.B (A0) 019FCC 4A10 TST.B (A0) 019FCE 67FC BEQ $019FCC ; wait for Vertical Interrupt 019FD0 4EB8 1612 JSR $001612.W ; call Play Music (skipping the "stop" part) 019FD4 xxxx DC.W #id ; "song ID" parameter for PlayMusic 019FD6 60FE BRA * ; freeze game
Hacking information:
PlayMusic routine: 001608 (stops music, waits for frame to finish, then starts music) GemsStart routine: 005CC4 (start GEMS sequence) GemsStop routine: 005D06 (stop all GEMS sequences) GEMS command area: A01B40~A01B7F
Bill's Tomato Game
Hacking information:
Note: Almost every value is a 2-byte word. (Big Endian)
Sound RAM: FF9000
NTSC/PAL Mode: FF9006/07 (01 - NTSC, enables extra delay, 00 - PAL)
NTSC Delay Cntr:FF9008/09 (counts 0..5 in NTSC mode, unused in PAL mode)
Pause Enable: FF900A/0B (01 - pause sound driver)
PlayMusic Slot: FF900E/0F (value is 01+)
Tempo Countdown:FF9010/11
Cur. Pattern: FF9012/13
Cur. Row: FF9014/15
Tempo: FF902C/2D
Playing State: FF902E
-> 00 - playing
-> FF - paused
Track RAM: FF903A (0C bytes per track, 6 tracks)
Total Frames: FF90B0/B1
Frames in Sec.: FF90B2/B3
Total Seconds: FF90B4/B5
Sound Driver Init routine: 0F91AA
Sound Driver Update routine: 0F928A
Track RAM
---------
00/01 - some Tick Counter
02/03 - Ticks until next event
04 - Event Type??
05 - Event Data
06 - ??
07-0B - unused (00)
Newman/Haas IndyCar featuring Nigel Mansell
ROM patch to play a song on the title screen:
offset hex bytes ASM code description 1C8C72 4E71 NOP ; skip SEGA screen 1CA4B6 4E71 NOP ; skip license screen 1C8A8E 4E71 NOP ; skip Aklaim screen 1C018E 303C 00xx MOVE.W #xx, D0 ; set song ID to play (0..5) 1C01A0 60FE BRA * ; freeze game after starting the song (to prevent screen changes etc.)
General ROM locations:
StopMusic: 070000 PlayMusic: 070004 (Register D0 = sound ID) UpdateMusic: 070008 LoadZ80Driver: 07000C SilencePSG: 070014 UpdateSFX: 07001C StopSFX: 070028 DoCarEngineSFX: 070030 Music Pointer Lists: 07173C (20h bytes per song, 6 songs) Sound RAM: FF8400
Sound IDs:
00 - Main Theme 01 - Racing BGM 02 - Qualified 03 - Hard Luck 04 - Race Results 05 - Ending
