I'v heard that both *CHR-ROM* and *CHR-RAM* could be loaded into the PPU?
My Question is:
1.What's the differencebetween CHR-ROM and CHR-RAM?
2.I know CHR-ROM are on NES Carts. But how about CHR-RAM?
3.If CHR-ROM and CHR-RAM are both on Carts? How could we know whether the on-board chip is CHR-ROM or CHR-RAM since iNES header doesn't give us this information.
4.Where should they be loaded to? PPU RAM for Pattern Tables? PPU RAM for NameTables?
I'v read a lot of articles, few has topic related to these. Thank you for your help.
CHRROM and CHRAM are both on the card, and both are loaded in pattern tables.
The foundamental difference is that CHRAM is written to by the programm (the programm writes graphics to PPU $0000-$1ffff via $2006/7), but CHROM can only be read by the CPU or PPU. Because 8kb of CHRRAM doesn't allow much graphics, it is often larger and have to be bankswitched. Bankswitch CHRAM is possible, but in most cases useless.
NB : The PPU has no RAM for pattern tables. The PPU just points to the chip that is on the cartridges (often trough a mapper), then the cartridge determine if it is ROM or RAM.
The iNES header DOES give information about CHRROM or CHRRAM.
If the bytes that tells how many banks of CHRROM the game has is 00h, then the game has 8kb of CHRRAM.
Also, if you're dealing at all with cartridges, I've found that it's usually printed on the PCB whether or not the game uses CHR-RAM or CHR-ROM. I'm not sure if that's any help or not.
JJ.Loki wrote:
I'v heard that both *CHR-ROM* and *CHR-RAM* could be loaded into the PPU?
My Question is:
1.What's the differencebetween CHR-ROM and CHR-RAM?
2.I know CHR-ROM are on NES Carts. But how about CHR-RAM?
3.If CHR-ROM and CHR-RAM are both on Carts? How could we know whether the on-board chip is CHR-ROM or CHR-RAM since iNES header doesn't give us this information.
4.Where should they be loaded to? PPU RAM for Pattern Tables? PPU RAM for NameTables?
I'v read a lot of articles, few has topic related to these. Thank you for your help.
Only a small number of games use both chr rom and chr ram, such as Pinbot, High Speed, and some pirate games. For Pinbot and High Speed (TQROM), requesting chr bank 8-F gives the same 8k of chr ram.
Thank you guys!
Dwedit wrote:
Only a small number of games use both chr rom and chr ram.
but how could we know one cart have both chr-rom and chr-ram? from the infromation contained in the iNes header?
en....I forgot to login,sorry. The reply above was posted by me.
Pin-Bot and High Speed, the two most well known CHR-ROM+CHR-RAM games, are both iNES mapper #119 and use the board NES-TQROM.