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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
02795 Cheat System Minor Always Jan 2, 2009, 02:12 Jan 2, 2009, 16:28
Tester salamando View Status Public Platform
Assigned To aaron Resolution Bugs That Aren't Bugs OS
Status [?] Resolved Driver cps2.cpp
Version 0.128u7 Fixed in Version Build
Summary 02795: all cps2.c sets: cpu main overclock starts at 74%
Description All cps2 games I tried start at overclock main cpu, 74%, when cpu clocking is enabled (cheat). I don't know if it's just the osd or actually set.
Steps To Reproduce Start any cps2 games with cheats enabled.
Additional Information
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Regression Version
Affected Sets / Systems all cps2.c sets
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Notes
2
User avatar
No.03462
Tafoid
Administrator
Jan 2, 2009, 03:02
I think I can explain why it does that.

cpu_set_clockscale(machine->cpu[0], 0.7375f); /* RAM access waitstates etc. aren't emulated - slow the CPU to compensate */

In 0.122u8, the actual main CPU clock was raised to 16 mhz to match that of the documentation and actual hardware as well as the above line was added. MAME is not at this time able to emulate the wait states needed for this hardware, so while the emulation shows 16mhz, the actual emulation is running at about 11.8mhz or so. Therefore, the 73% you see is the adjusted CPU rate (11.8/16)*100 = 73.75%.

I'm not certain if there is anything that can be done to correct this - or if it's actually a 'bug'.
User avatar
No.03466
aaron
Developer
Jan 2, 2009, 04:00
This is a result of the kludge Tafoid mentions. It is not a bug.