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ID Category [?] Severity [?] Reproducibility Date Submitted Last Update
05488 Debugger Minor Always Apr 6, 2014, 02:36 Apr 8, 2014, 14:26
Tester rimsky82 View Status Public Platform MESS (Self-compiled)
Assigned To Resolution Open OS Windows Vista/7/8 (64-bit)
Status [?] Confirmed Driver
Version 0.152 Fixed in Version Build 64-bit
Fixed in Git Commit Github Pull Request #
Summary MESS-specific 05488: megadriv genesis: Genesis ROM is uneditable via command nor memory window
Description Genesis ROM is uneditable. Whether using commands in the debugger or typing to the memory window, it won't change.
Steps To Reproduce Play any game in Megadrive/Genesis with the debugger enabled and attempt to edit any words in the ROM range (0 - 0x3FFFFF I believe).
Additional Information Not being able to edit the ROM during the game makes the emulator useless to try to hack the game to make new Game Genie codes or any other ASM related cheats. Including any MESS cheats that manipulate the ROM.
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Affected Sets / Systems megadriv genesis
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4
User avatar
No.10538
Tafoid
Administrator
Apr 6, 2014, 19:10
edited on: Apr 6, 2014, 19:17
Might it make a difference if you are loading the same via the normal "picker" style or are you using the softlist?
I can confirm I cannot change the memory in that range with the debug interface, normally using maincpu.mw@address=value I suspect most of not all externally cart based systems are in the same boat as I had an issue dealing with PCE/TG-16 as well some months back.
User avatar
No.10539
rimsky82
Tester
Apr 6, 2014, 19:27
it doesn't seem to make a difference how it's loaded. (Verified with an md file on genesis).

I will add that I think this might have started when the genesis was slotified a few months back. You may be right, that may have something to do with it.
User avatar
No.10547
Kale
Developer
Apr 8, 2014, 13:25
As a rule of thumb, no ROM for any system can be edited from the debugger. And I know it too well because I've needed it in some circumstances and needed to resort to code it manually or use debug tricks. Debugger treats your memory writes as if the program is trying to write to ROM (which it fails for obvious reasons)

Now, I'm not against this feature, but how to implement it?
User avatar
No.10548
rimsky82
Tester
Apr 8, 2014, 14:26
I may be misinformed, but I just want to be certain we are on the same page. I'm not trying to edit the ROM directly, say to the mdslot region, but rather to the ROM loaded in memory in the maincpu region. Whether or not that makes a difference, I don't know. I will also add this does work in other systems, such as nes, and it worked for genesis in the past, like was already stated, possibly before the system was slotified.