How to change an 8-bit value in RAM on Gens or PicoDrive emulator?

[AlexWong]

If I want to change an 8-bit value in RAM on Gens on PC or PicoDrive on PSP, how to do this?

For example:

FFC100 //I don't want to change the 8-bit value on this address.
FFC101 //I want to change the 8-bit value on this address to 99 (0x63) for example.
FFC102 //I don't want to change the 8-bit value on this address.

If I enable a Pro Action Replay code of FFC101:0063, will it change the 8-bit value on FFC100 or FFC102 to 00?

By the way, I find that Pro Action Replay codes are not unified on all Sega Genesis emulators. For example, when I play Shining Force (USA) on Gens or PicoDrive, I use the following codes to change the gold value to 999999 (0x000F423F):

FF9C8E:000F
FF9C90:423F

However, when I play this game on MD.emu on Android, I find that this emulator makes LOGIC OR operations. For example:

FF9C8E:000F //16-bit value on FF9C8E LOGIC OR 000F
FF9C8F:000F //16-bit value on FF9C8F LOGIC OR 000F
FF9C90:423F //16-bit value on FF9C90 LOGIC OR 423F
FF9C91:423F //16-bit value on FF9C90 LOGIC OR 423F

Although LOGIC OR operations can change an 8-bit value and do not affect its adjoining values, but this 8-bit value can only become larger. It's very annoying that MD.emu uses a wrong algorithm on Pro Action Replay codes.

[Tony H]

I'm pretty sure some versions of Gens let you enter PAR codes like this:

FFC101:63

Just try a single byte like that and see if it works.

If that doesn't work, post which game your playing and exactly what you're trying to do and will see if we can figure something out.

I know what you mean about how different Genesis emulators handle PAR codes differently. Pain in the ass.

[AlexWong]

Yes, you are right! I never found that Gens v2.10-mk2 allows me to add PAR codes like XXXXXX:YY, and they do work fine, do not affect the adjoining values. However, PicoDrive is still unable to change an 8-bit value only. It must change a 16-digit value per code. Anyway, there is at least one emulator allows me to hack RAM more accurately. Thanks!