カテゴリ 重要度 ステータス 解決状況 登録日時 最終更新
速度最小解決済み修正済み2010-02-10 06:452010-02-11 06:47
 
テスターOliver_A担当者Tafoidソースmrdo.cpp
バージョン0.136u2発生バージョン修正バージョン0.136u3
フラグ実機・資料検証済み
セット mrdo
セット詳細
mrdo - ミスターDo!
 
概 要XTAL値が間違っているのでリフレッシュレートやゲーム速度の問題がある。
詳 細The driver for Universal's Mr. Do has the wrong speed for the CPU, sound and screen refresh rate.

Reason: the schematics have the wrong crystal oscillator values.

Mr. Do uses 2 crystals, each for the video timing, and CPU / Sound speed.

In the schematics, the crystal for the video timing is 20Mhz and for the CPU/Sound 8Mhz, which is divided by 2.

On the real Mr. Do PCB (8201 revision), the values for the video timing is 19.6 Mhz and for the CPU / sound 8.2Mhz.

That means, the real values for the game are:

CPU: Z80 clocked at 4.1 Mhz.
Sound: 2*SN76489 clocked at 4.1 Mhz.

The change in the video oscillator frequency also affects the refresh rate.
再現手順Locate a real Mr. Do PCB and compare the oscillator frequencies with those of the schematics. On revision 8201 PCB, they will not match.
追加情報I have included 2 photos taken from my ORIGINAL Mr. Do PCB which verify my claims.

The board was not modified in any way. In fact, it would be quite hard to purchase the two oscillators, because the frequencies are so odd.

Note: this descripancy in clock speeds is most probably also responsible for the off-key music in Mr. Do Run Run.
 
添付ファイルzip fileMrDo_PCB.zip (2010-02-10 06:45)