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| | Previous Messages | Posted By
MIK
on 2024-02-22
18:14:52
 |  Re: Rockman built-in cheat mode
I just tried Ulysses idea of just resetting before you posted Waz and all is fine with the C16/Plus4 compatible version on that C16 now. It's running right now and just got a rusty 18k. 
Sorted and a music off note is going in all my copies for safe keeping and future reference.
Thanks guys!
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Posted By
Waz
on 2024-02-22
17:27:14
| Re: Rockman built-in cheat mode
Thanks for that info @MIK - really useful, and as @Ulysses777 says, a reset appears to work (which is what I did when testing, I did reset rather than RUN/STOP and reset.)
All it basically does is to place an RTS at the routine at $1E53 that checks so returns straight back from the subroutine called. That subroutine uses $7E and $7F in zero page as counters, $7E to do a count to $0C, and only then read the value of $7F to set the notedata offset from $14C4,X, which has 60 ($3C) bytes of notes in a table, which are set into $FF0F as needed and then with a small subroutine to set $FF11 also. Bear in mind on some memory maps I've read, those $7E and $7F zero page bytes can be temporary set for note and volume also.
If you never wanted to even go there, you could either fill $14C4-$14FF with zero (and add a RTS at $1E75 so that $FF11 isn't set either), or the JSR $1E53 is at $1CDF in memory, so you could replace those bytes with say NOPs instead.
It may be worth seeing if any of these methods work on the revision A board with the C16 and Plus4 compatible version, and should be compatible also with other releases, so you can use either of:
Zero bytes in ingame music data and RTS to stop $FF11 being set:
FOR A=0 TO 59:POKE 5316+A,0:NEXT:POKE 7797,96
Stop subroutine being called:
POKE 7391,234: POKE7392,234: POKE7393,234
These may be alternatives to try but don't have a C16 Rev A to test here.
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Posted By
Ulysses777
on 2024-02-22
16:28:44
| Re: Rockman built-in cheat mode
I've had a quick look, and it seems to crash there if you exited the game with Reset+Run/Stop, then tried to enter the cheat from BASIC.
If you exit the game with Reset only, it seems to work.
On another note, Rockman is another game with a stack overflow problem (along with it's Vic20 counterpart). After ~55 games, the stack overflows and crashes the game.
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Posted By
MIK
on 2024-02-22
13:17:05
| Re: Rockman built-in cheat mode
Good work, how the game should of been all along. 
Just a small update and nothing to worry about as this is just an obsession.
I have a Rev.A C16 which I call the Shaun Southern revision as it loads early versions of his Vegas Jackpot, later revision.A C16's will not load it, nor will Rev.B C16's or Plus/4.
So the so called Shaun Southern revision which loads everything and why I use it as a main machine for loading 16k stuff... Your music cheat works great when using the C16 Only version. The game crashes however if you die using the C16/Plus4 compatible one on this revision. When you die the full screen dude shows up, it plays 1 bar of the death tune and quits to either Basic or the Monitor, chars are all the game gfx lol.
Just an obsession any way, I wouldn't normally use the C16/Plus4 compatible one on a C16, I would put this down as just one of those things. Not an issue, and gives reason to own a C16 ONLY copy for this revision of C16 lol.
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Posted By
Waz
on 2024-02-21
17:22:12
| Re: Rockman built-in cheat mode
I might see if I can do a POKE or a monitor cheat to turn the in-game music off (but keep the sound effects).
EDIT: Done it! It keeps all the other sounds intact, but never plays the in-game tune (much to the delight of some). So either:
1E53 60
POKE 7763,96
I'll add those to the cheats section shortly, but that should be helpful for some of you. I've tested this with both Novaload versions (C16 only and fully compatible Plus/4 one) and works in both cases.
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Posted By
MIK
on 2024-02-20
20:15:08
| Re: Rockman built-in cheat mode
I like the jingle when you get a gem and the title screen music does the job, just that in-game music is out of tune and gives me the feeling I'm in a nut house going crazy lol.
Quality game though and a C16 classic.
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Posted By
C64Mark
on 2024-02-20
16:34:40
| Re: Rockman built-in cheat mode
hahahaha. It is strange that when I played this as a child, the music never bothered me and I loved the game. Now, I find it hard to concentrate on the game with the tune playing...
Csabo - I will try that now
Yes that seems to have worked.
Interestingly, the game checks the border colour to see if the cheat is active. So simply changing FF19 to anything other than black will also switch on the cheat mode
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Posted By
MIK
on 2024-02-20
15:30:09
| Re: Rockman built-in cheat mode
Wow after all these years, intresting find!
If you stumble across one that officially allows you to turn the music off please share...
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Posted By
Csabo
on 2024-02-20
15:17:14
| Re: Rockman built-in cheat mode
Awesome find! Thank you for bringing this up - P4W is here for everyone to edit and contribute. If you can't do something, or if it's not obvious, please speak up That said, there now should be an "[ add cheat ]" link on the Rockman page, would you mind trying that?
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Posted By
C64Mark
on 2024-02-20
14:01:48
| Rockman built-in cheat mode
Not sure how to edit the game page to add a cheat, but just found a built-in cheat for Rockman...
During the game, press asterisk(*) then cbm+M. The border will turn blue. You can now move between screens without collecting any diamonds.
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