help to expand a master system rom

[SatY Traduções]

Hi, I'm Brazilian and I'm writing a message using an automatic translator, I hope my message is clear. Came here hoping to get some help, I only know the basics of the Z80 and I need to add a splash on a game I'm translating. A splash is already ready, but you need to expand a rom so that it is already embedded.

To expand the rom I created a label at $80000 which resulted in a size of 51kb. Change the header at address $00007FFF according to the size of the rom and finally insert all the splash routines in the expanded area (end of the rom).

That didn't work, for some reason nothing that is in the expanded part is recognized. can anybody help me? If you are interested in teaching me this or anything related to the z80 I would greatly appreciate it.  :riso:

game: Danan the Jungle Fighter (U)

[FlashPV]

You should ask at SMS Power! Instead:
https://www.smspower.org/forums/f3-Development

[SatY Traduções]

thanks

[FAST6191]

Expand as in make larger or expand as in alter the program flow to display your extra splash screen?

Expanding ROMs to make them larger varies between systems and often type of ROM on that system. I am not particularly familiar with the master system but most 8 bit machines in the most basic cartridges had sharply limited memory, this means aside from some of the simpler games you probably have to deal with bankswitching/mappers/memory controllers or something that change what ROM area the system is shown to something else. You hope there is some space in the existing setup but you might not find any or find yourself able to claw some back from useless data, in that instance you can consider changing to another type (maybe a later game type had more still you can fake being -- most flash carts and emulators don't care after all) and if it is just for a splash screen at the start you also possibly dodge some of the annoying issues that you would encounter if you did it later in the game.

Altering program flow should not be so bad for a splash screen (presumably a we translated this type of thing). Most games usually have several and when the next one loads (say be copying new tiles to VRAM or whatever the SMS calls video memory, something you can easily detect with a breakpoint from a debugger) you would instead jump in just before, add in your own load from ROM to VRAM, order tiles on screen and then jump back to where the original "next" screen was loading after however long you deem necessary.