02795: all cps2.c sets: cpu main overclock starts at 74%

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	capcom/cps2.cpp
Version	0.128u7	Fixed in Version		Build
		Fixed in Git Commit		Github Pull Request #

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
Github Commit

Flags
Regression Version
Affected Sets / Systems	all cps2.c sets

Attached Files

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'.
No.03466 aaron Developer Jan 2, 2009, 04:00	This is a result of the kludge Tafoid mentions. It is not a bug.

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'.

No.03466

aaron

Developer

Jan 2, 2009, 04:00

This is a result of the kludge Tafoid mentions. It is not a bug.