|サウンド||低||仮承認||未処理||2014-01-30 14:06||2020-10-05 00:51|
|セット||1942 & clones, nemesis & clones, possibly others|
1942 - 1942 (Revision B)
nemesis - グラディウス / Nemesis (ROM version)
|詳 細||Looking through MAME's source code and comparing schematics of both 1942 and Nemesis, there is an error in the loads on the chips which you can see below.|
Both games and their clones, possibly even other games using the same driver, do not have the correct loads on their AY-3-8910 outputs. In nemesis.c, the AY-3-8910 interfaces are set to use the default loads of 1Kohm, which is completely wrong. If you look at the AY-3-8910's audio outputs in the Nemesis schematic, there is no load whatsoever on either AY-3-8910's outputs.
Similarly, 1942 has the same issue. It uses the generic AY-3-8910 interface in ay8910.c, which is wrong. This game has a 10Kohm load on the outputs.
Other games may have the same incorrect loads, but these are two that I can confirm use the wrong loads.
Images of each game's schematics are attached with the loads (or lack thereof for Nemesis) enclosed in a red square.
Schematics are from the following links:
|追加情報||The Nemesis loads being incorrect may be related to one of the many audio errors I reported in issue 03539.|
|添付ファイル||1942 AY-3-8910 outputs.png (2014-01-30 14:06) |
|Nemesis AY-3-8910 outputs.png (2014-01-30 14:06) |