Emulator Cheats

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1. Start MAME as you would normally - don't forget you must use the debug MAME build with either -debug on the commandline or DEBUG 1 in the ini file 

2. You will find that after a short while MAME will be on the debugger screen, at this stage just press F12 to start the game. [REMEMBER F12 in the debugger will return you to the game] 

3. Commence play 

4. Start a Energy Search and reduce the results using standard methods. In the example I reduced the results to 2 possibles 100AC6 & 10373B, by using watches I can discount 100AC6 as it's the time location. So that leaves us with 10373B 80 = Full Energy. NOTE: You have to find the value as quickly as possible because the location will change the next time the level changes, so you would have to start the search from the beginning. You can test the address you find by poking it directly if it's the correct location you will find it will have the desired affect on that level. 

5. Press the tilde key (the tilde key is the key under Esc and about TAB and the the left of 1). You will now be in the debugger, remember the fact that we found the address 0010373B in step 4 (Note the preceding 0s - we will need them). 

6. Press TAB 3 times so that the cursor is in the address window. Now press S to commence a search and type in the value as per step 5...but drop the last byte as that will be part of the index. So in this case we would type in 00 10 37, then press RETURN to execute the search - you can repeat the search by  pressing S and hitting RETURN (the last search values are still set). For every search result note down the address, you can safely ignore any results in ROM locations or where it crosses word boundaries (ie it shows as XX00 1037 instead of 0010 37XX). In this example you will find that S 00 10 37 only returns one ROM location at 00003680, so we can safely ignore it. However, there are no other occurences so we are goosed.....or are we? 

7. If there are no possibilities then remember that the location we are looking for contains an address that hopefully points to a page of memory limited in size. In most cases this seems to be no greater than 256 bytes and is mostly forward indexed (+ve rather than -ve). So assuming that 10373B is the extreme case it is 256 bytes away from the start of the memory page base location, then the base location of the page would be 10363C. So we need to repeat Step 6 but this time with S 00 10 36 as the search instruction, ignoring ROM locations and word boundary crossing, from this we get the following results:- 

Address     Contents 
100A46       00103680 
100A5E       00103680 
102AEC       00103680 
102D2C       00103680 
103F2C       00103680 
10404C       00103680 
104DCC       00103680 
10500C       00103680 
1057EC       00103680 
105A2C       00103680 
105C6C       00103680 
10644C       00103680 

8. From the Step 7 results you can see that all the results point to a page of memory starting at 00103680, since we know the energy location is 0010373B we can work out that the index value is = BB (Cheat Location - Start Address of page = 10373B -103680). 

9. Now you need to narrow the location down either by loads of watches on several levels or by excessive testing, personally I place a watch on all the locations and try the first location first, second location second etc etc. [ NOTE: A lot of neogeo games which utilise dynamic addressing seem to like to use a value in the range 100AXX as the pointer location. ] Here are the cheats to try first... 


:samsho2:83000000:00100A46:00000080:000000BB:Infinite Energy PL1 [POSSIBILITY NO. 1] 
:samsho2:83000000:00100A5E:00000080:000000BB:Infinite Energy PL1 [POSSIBILITY NO. 2] 
:samsho2:83000000:00102AEC:00000080:000000BB:Infinite Energy PL1 [POSSIBILITY NO. 3] 
:samsho2:83000000:00102D2C:00000080:000000BB:Infinite Energy PL1 [POSSIBILITY NO. 4] 

{ One more interesting thing to note, you may find that several locations will have the desired affect as the pointers maybe held in several places in memory, it really doesn't matter which one you use. }

10. Once you find out the location which works bear in mind that the game will use the same page for other things like Power etc, Note PL2 will generally use a different page though the location holding the pointer is generally right next to the pointer for the other Player (the index will generally be the same though...which is nice :) ). 

For samsho2 we hence have these dynamic cheats:- 

:samsho2:83000000:00100A46:00000080:000000BB:Infinite Energy PL1 
:samsho2:83000001:00100A46:00000000:000000BB:Drain All Energy Now! PL1 
:samsho2:83000000:00100A46:00000020:000000F0:Always have Maximum Power PL1 
:samsho2:83000000:00100A46:00000000:000000F0:Always have Minimum Power PL1 
:samsho2:83000000:00100A4A:00000080:000000BB:Infinite Energy PL2 
:samsho2:83000001:00100A4A:00000000:000000BB:Drain All Energy Now! PL2 
:samsho2:83000000:00100A4A:00000020:000000F0:Always have Maximum Power PL2 
:samsho2:83000000:00100A4A:00000000:000000F0:Always have Minimum Power PL2 

Dynamic Cheat Finding Method (c) Pugsy 2000-2002 ;-) 
 

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stb r3, r12(0x20)