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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
06769 Core Major Always 27 days ago 26 days ago
Tester demotester View Status Public Platform MAME (Official Binary)
Assigned To Resolution Open OS Other
Status [?] Confirmed Driver bbc.cpp
Version 0.191 Fixed in Version Build 32-bit
Summary MESS-specific 06769: bbcm: BCD test failed on 65SC02
Description B-Em forum -> http://www.stardot.org.uk/forums/viewtopic.php?f=4&t=10823&start=240#p166332

The latest branch of B-Em WinBuild -> http://www.stardot.org.uk/forums/download/file.php?id=28847
The latest branch of B-Em has fixed 65SC02 BCD -> so BBC Master emu passes 65SC02 BCD test in "6502test.ssd"!
Note: "6502test.ssd" find inside the disc folder!
Steps To Reproduce How to run "6502test.ssd" on MAME bbcm driver: Mount the disc on bbcm driver and press SHIFT+F12 keys!

When run the "6502test.ssd" in MAME bbcm driver, the CPU is detected as 65C02 instead of 65SC02?
Also, the Basic BCD test with 6502 and 65C02 passes but fails with 65SC02!

According to this, the BBC Master driver in MAME seems does not using 65SC02 CPU! (as other emus do)
In MAME bbcm driver "Machine Information" it says: 65SC02 2MHz!
Additional Information
Flags
Regression Version
Affected Sets / Systems bbcm
Attached Files
png file icon mame_bbcm_6502test.png (6,400 bytes) 27 days ago Uploaded by demotester
MAME bbcm test detection!
demotester
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Notes
1
User avatar
No.14457
hap
Developer
26 days ago
I don't know why autodetection goes wrong.

But the reason the BCD test fails on 65C02 is because ADC/SBC decimal mode is slightly different on CMOS CPUs. MAME doesn't emulate this difference.
I didn't look into it further (don't know the exact differences)