[ オリジナルレポート ]

BugID: #05438

カテゴリ 重要度 ステータス 解決状況 登録日時 最終更新
サウンド仮承認未処理2014-01-30 14:062020-10-05 00:51
 
テスターAce担当者 ソース
バージョン0.152発生バージョン修正バージョン
フラグ
セット 1942 & clones, nemesis & clones, possibly others
セット詳細
1942 - 1942 (Revision B)
nemesis - グラディウス / Nemesis (ROM version)
 
概 要AY-3-8910の出力抵抗が間違っている。
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:

http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/1942_Schematics_%28Capcom%29.pdf
http://arcarc.xmission.com/PDF_Arcade_Manuals_and_Schematics/Nemesis%20Schematics.pdf
再現手順 
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png file1942 AY-3-8910 outputs.png (2014-01-30 14:06)
png fileNemesis AY-3-8910 outputs.png (2014-01-30 14:06)