[GBS] No sound when playing "Top Gear 2 Pocket"
Closed this issue · 2 comments
Wohlstand commented
Original report by brianpow (Bitbucket: brianpow, GitHub: brianpow).
No sound when playing "Top Gear 2 Pocket" with gme_player
The gme_player window shows as normal but no sound and only a flat wavefront bar shown
Other GBS player such as NEZPlug and MiniGBS work fine
Wohlstand commented
Original comment by Leandro Nini (Bitbucket: [Leandro Nini](https://bitbucket.org/Leandro Nini), ).
Did a debug trace on MiniGBS:
0242: f0 40 | SP:dff7 AF:00a0 BC:0000 DE:0000 HL:0100 | ldh a, [$ff40] | [00]
* * * + Audio read : ff40 -> 0 + +
0244: cb 7f | SP:dff7 AF:00a0 BC:0000 DE:0000 HL:0100 | bit 7, a |
0246: 28 09 | SP:dff7 AF:00a0 BC:0000 DE:0000 HL:0100 | jr z, +9 |
It reads from $ff40 (LCD control) and if bit 7 is set enters an infinite loop. Not sure about the rationale 😕
Looking at the other emulators the IO area ($FF00 – $FF7F) is zeroed out at startup, which makes the tune play fine, while on gme it is set to $ff.
Will send a fix later.