CutterCross
Active member
Okay I'm not sure how this is going to fit in on this forum seeing how it's not NESmaker related, but I know a decent amount of users here might be interested in stuff like this. This may need to be moved to a specialized category.
View: https://www.youtube.com/watch?v=KCQaO61_ahY
I'm experimenting with traditional NESdev and other mapper types. I finished a test project that uses GTROM as its mapper. GTROM has dedicated memory to fill all 4 PPU nametables with unique data, and it can hold 2 pages of 4-screen nametable data that can be swapped into the PPU memory window on the fly. It also has two 8 KiB pages of CHR-RAM, as opposed to UNROM 512's four 8 KiB pages. GTROM also has 2 LEDs [green and red] on the board that can be controlled, but no emulator / flashcart implementation supports this.
GTROM's most difficult aspect to develop for is it's 32 KiB PRG-ROM page size. UNROM 512 has a 16 KiB page size, and this allows for one 16 KiB bank to remain loaded for the entire program, and the other 16 KiB can be swapped out with other banks. This "static bank" layout can't be done with GTROM, because it can only bankswitch the entire 32 KiB. So to work with this, you have to duplicate your "static" data in the same locations on every bank, and be very careful in its setup so that your program doesn't crash upon switching banks.
This ROM tests the 4-screen mirroring setup and nametable page toggle, as well as the 32 KiB page bankswitching via 7bit PCM streaming. The LEDs have toggle support with the B and A buttons, but I have no way of testing this right now until I can get my hands on an actual GTROM board.
I'm experimenting with traditional NESdev and other mapper types. I finished a test project that uses GTROM as its mapper. GTROM has dedicated memory to fill all 4 PPU nametables with unique data, and it can hold 2 pages of 4-screen nametable data that can be swapped into the PPU memory window on the fly. It also has two 8 KiB pages of CHR-RAM, as opposed to UNROM 512's four 8 KiB pages. GTROM also has 2 LEDs [green and red] on the board that can be controlled, but no emulator / flashcart implementation supports this.
GTROM's most difficult aspect to develop for is it's 32 KiB PRG-ROM page size. UNROM 512 has a 16 KiB page size, and this allows for one 16 KiB bank to remain loaded for the entire program, and the other 16 KiB can be swapped out with other banks. This "static bank" layout can't be done with GTROM, because it can only bankswitch the entire 32 KiB. So to work with this, you have to duplicate your "static" data in the same locations on every bank, and be very careful in its setup so that your program doesn't crash upon switching banks.
This ROM tests the 4-screen mirroring setup and nametable page toggle, as well as the 32 KiB page bankswitching via 7bit PCM streaming. The LEDs have toggle support with the B and A buttons, but I have no way of testing this right now until I can get my hands on an actual GTROM board.