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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
07892 Gameplay Minor Always Mar 1, 2021, 08:48 Mar 1, 2021, 11:16
Tester Augusto View Status Public Platform SDLMAME
Assigned To Resolution Open OS Linux (64-bit)
Status [?] Confirmed Driver galaga.cpp
Version 0.229 Fixed in Version Build 64-bit
Fixed in Git Commit Github Pull Request #
Summary 07892: sxeviousj: Inserting coin automatically start 2 player game with issues
Description Insert one coin.
Automatically start 2 player game not using the inserted credit.
Solvalou goes totally to left without player input.
When that gameplay end is possible start an new gameplay with correct control input.
To play need insert one coin wait to both 2 player game end or insert coin and after reset.
Only affect sxeviousj.
Steps To Reproduce
Additional Information
Github Commit
Flags
Regression Version 0.221
Affected Sets / Systems sxeviousj
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No.18502
Tafoid
Administrator
Mar 1, 2021, 11:16
edited on: Mar 1, 2021, 11:17
In particular, work done on April 25, 2020 seems to be the culprit.
Namco custom chip improvements
https://github.com/mamedev/mame/commit/3a6317b0f47a1596777537b7c7544818076f9397

Given the fact that it 'clears up' after the failed start tends to suggest a race condition as mentioned in the source text of one of the custom control chips.
    Note that Xevious has a potential race condition at 0xE9. It checks if
    the control register is 0x10 (chip disabled), then 4 instructions later
    acts on that check. If an NMI occurs between, it can crash.

Why it only affects SXEVIOUSJ, it is unknown. All other tested xevious/clone sets do not exhibit this under testing.