Double Dragon overclocking cheat

[terryhan]

It's not strictly speaking a cheat, but it uses the cheat.dat file, so I was wondering if you could help me out.
I'm trying to make three cheats to overclock the three processors in Double Dragon (by 200%), but they don't seem to work. Here's what I'm using (from the Mameworld forum):

ddragon:65004000:00000000:00020000:00000000:Overclock CPU#1
ddragon:65004000:00000001:00020000:00000000:Overclock CPU#2
ddragon:65004000:00000002:00020000:00000000:Overclock CPU#3

They appear in the cheat selection, but when I select them they don't work, or at least, don't have the same effect as turning each processor up to 200% on the MAME menu.

[kelvSYC]

All cheats using the new cheat engine must start with a colon. Since these lines don't start with a colon, the cheat engine is misinterpreting them as old cheat engine lines.

[terryhan]

Thanks very much. And to think I deleted those colons because the cheats didn't appear in the cheat menu.

Can I ask, if I wanted to overclock the processor by 150% instead of 200%, would I simply change the 00020000 value to 00015000?

[Pugsy]

Overclocking cheats shouldn't appear in the cheat list....they autoload on starting MAME, so it's invisible to the user.

How it works can be found in the cheat.c file in the MAME source archive. Or you can find it mentioned in the lead in of the cheat file.

Code: Select all

; Overclock: (01100101 -------- -1------ --------) 0x65004000
;
;                       Overclocks a CPU. Put the CPU index you want in the address field, and the overclocking amount in the data field.
;                       Use 16.16 fixed point notation for the overclocking amount.
;
;                       Example 1: overclocking CPU #0 by 200%
;                       :gamename:65004000:00000000:00020000:00000000:
;
;                       Example 2: overclocking CPU #3 by 125%
;                       :gamename:65004000:00000003:00014000:00000000:
;
;                       To convert a percent to 16.16 fixed point notation, take the percentage as a decimal value (eg. 65% = .65) and
;                       multiply it by 65536. Then, convert the value to hex.

So to overclock it by 150% it would be 00018000

ie 1.5 * 65536 = 98304 in decimal = 18000 in hex

[terryhan]

Again, thanks.