SEGA CD Temporary offset hex /ISO file patching?

[GoogleCodeExporter]

So how about it? 

You know just like the Game Genie does to Genesis/MD games. I know it would 
never work on a real one but can you consider adding it to this already great 
port?

Example:

One of Tony Hedstrom's codes/hacks:

Changing the value at 0x022E2A2 in the ISO (binary mode2/2352 ISO) from:
33FC000000FF1512
to
6006000000FF1512

on Sonic CD (US version) allows Sonic not to lose any rings when he's hit.

I have tried this before (022E2A2:6006) on the emulator before but it doesn't 
work. I was thinking since PAR codes work maybe this would/could too.

Original issue reported on code.google.com by 47isc...@gmail.com on 27 Jun 2014 at 6:09

[GoogleCodeExporter]

This is completely different than ROM patching: ISOs are accessed by sectors 
(2048 bytes), a new sector being read every 1/75s so temporary patching the 
wole ISO is not possible, the file being read only partially when required. It 
would require looking for the sector address vs the address to patch everytime 
you read a new sectors, which would be very unefficient (even with patching 
disabled, the code would still need to check at every sectors if patching is 
enabled or not).

ROM patching won't work since there is no ROM and the memory map with Mega CD 
is completely different than with a normal cartridge so it makes absolutely no 
sense trying ROM patches like you did.

RAM patches are still working but will only affect the Mega Drive side RAM.

Original comment by ekeeke31@gmail.com on 27 Jun 2014 at 10:45

• Changed state: WontFix
• Added labels: Type-Enhancement

[GoogleCodeExporter]

Okay. Just wondering.

Original comment by 47isc...@gmail.com on 27 Jun 2014 at 5:08