clearmem
clears the mem and ppu stuff
This commit is contained in:
Tyrel Souza
parent
fc0bf0edb7
commit
e58a6330d9
1
.gitignore
vendored
Normal file
1
.gitignore
vendored
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tags
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18
Makefile
Executable file
18
Makefile
Executable file
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###############################################################################
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# Rule to assemble and link all assembly files
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###############################################################################
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build:
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ca65 clearmem.asm -o clearmem.o
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ld65 -C nes.cfg clearmem.o -o clearmem.nes
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###############################################################################
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# Rule to remove all object (.o) files and cartridge (.nes) files
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###############################################################################
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clean:
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rm *.o *.nes
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###############################################################################
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# Rule to run the final cartridge .nes file in the FCEUX emulator
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###############################################################################
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run:
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fceux clearmem.nes
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104
clearmem.asm
104
clearmem.asm
@ -1,64 +1,64 @@
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; The iNES Header contains a total of 16 bytes with
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;; The iNES header (contains a total of 16 bytes with the header flags)
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;; flags at $7FF0
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; https://www.nesdev.org/wiki/INES
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.segment "HEADER"
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.segment "HEADER"
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.org $7FF0
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.byte $4E,$45,$53,$1A ; 4 bytes with the characters 'N','E','S','\n'
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.byte $4E,$45,$53,$1A ; 4 bytes with chars NES\n
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.byte $02 ; How many 16KB of PRG-ROM we'll use (=32KB)
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.byte $02 ; 1 byte how many 16kb in pgm-rom
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.byte $01 ; How many 8KB of CHR-ROM we'll use (=8KB)
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.byte $01 ; 1 byte how many 8kb chr-rom
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.byte %00000000 ; Horz mirroring, no battery, mapper 0
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.byte %00000000 ; Horiz mirroring, nothing else
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.byte %00000000 ; mapper 0, playchoice, NES 2.0
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.byte %00000000 ; Flags 7 - nothing
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.byte $00 ; No PRG-RAM
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.byte $00 ; Flags 8 - no PGM-RAM
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.byte $00 ; NTSC TV format
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.byte $00 ; NTSC
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.byte $00 ; Extra flags for TV format and PRG-RAM
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.byte $00 ; no PGM-RAM
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.byte $00,$00,$00,$00,$00 ; Unused padding to complete 16 bytes of header
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.byte $00,$00,$00,$00,$00 ; unused padding to complete 16bytes
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; PGM-ROM code located at $8000
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; PRG-ROM code located at $8000
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.segment "CODE"
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.segment "CODE"
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.org $8000 ; start of program rom
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Reset handler (called when the NES resets/powers-on)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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Reset:
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sei ; Disable all IRQ interrupts
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cld ; Clear the decimal mode (unsupported by the NES)
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ldx #$FF
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txs ; Initialize the stack pointer at $01FF
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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inx ; Increment X, causing a roll-off from $FF to $00
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;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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RESET:
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sei ; set interrupt disable - disable all IRQ
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cld ; clear decimal mode BCD flag (unused)
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ldx #$FF ;
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txs ; initialize stack pointer at $01FF
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;;;;; LOOP ALL MEMORY POSITIONS FROM 00 to FF clearing
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txa ; A = 0
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ClearRAM:
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sta $0000,x ; Zero RAM addresses from $0000 to $00FF
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sta $0100,x ; Zero RAM addresses from $0100 to $01FF
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sta $0200,x ; Zero RAM addresses from $0200 to $02FF
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sta $0300,x ; Zero RAM addresses from $0300 to $03FF
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sta $0400,x ; Zero RAM addresses from $0400 to $04FF
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sta $0500,x ; Zero RAM addresses from $0500 to $05FF
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sta $0600,x ; Zero RAM addresses from $0600 to $06FF
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sta $0700,x ; Zero RAM addresses from $0700 to $07FF
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inx ; X++
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bne ClearRAM ; Loops until X reaches 0 again (after roll-off)
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lda #$0 ; A = $0
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LoopForever:
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inx ; increment X from $FF to $0
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jmp LoopForever ; Forces an infinite loop
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MemLoop:
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sta $0,x ; store the value of A (zero) into $0 + X
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dex ; X--
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bne MemLoop ; loop back to MemLoop if X is not 0
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; NMI interrupt handler
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;; NMI Handler - executed every time NMI interrupt
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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NMI:
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NMI:
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rti ;return from interrupt
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rti ; Return from interrupt
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; IRQ Handler - executed every time IRQ interrupt
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;; IRQ interrupt handler
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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IRQ:
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IRQ:
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rti ;return from interrupt
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rti ; Return from interrupt
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Vectors with the addresses of the handlers that we always add at $FFFA
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;; SEGMENTS
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.segment "VECTORS"
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.segment "VECTORS"
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.org $FFFA ; 6502 will always start at $FFFA
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.word NMI ; Address (2 bytes) of the NMI handler
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.word NMI ; address of the NMI Handler label
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.word Reset ; Address (2 bytes) of the Reset handler
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.word RESET ; address of the RESET Handler label
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.word IRQ ; Address (2 bytes) of the IRQ handler
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.word IRQ ; address of the IRQ Handler label
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18
helloppu/Makefile
Executable file
18
helloppu/Makefile
Executable file
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###############################################################################
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# Rule to assemble and link all assembly files
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###############################################################################
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build:
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ca65 helloppu.asm -o helloppu.o
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ld65 -C nes.cfg helloppu.o -o helloppu.nes
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###############################################################################
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# Rule to remove all object (.o) files and cartridge (.nes) files
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###############################################################################
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clean:
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rm *.o *.nes
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###############################################################################
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# Rule to run the final cartridge .nes file in the FCEUX emulator
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###############################################################################
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run:
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fceux helloppu.nes
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104
helloppu/helloppu.asm
Executable file
104
helloppu/helloppu.asm
Executable file
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Constants for PPU registers mapped from addresses $2000 to $2007
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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PPU_CTRL = $2000
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PPU_MASK = $2001
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PPU_STATUS = $2002
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OAM_ADDR = $2003
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OAM_DATA = $2004
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PPU_SCROLL = $2005
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PPU_ADDR = $2006
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PPU_DATA = $2007
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; The iNES header (contains a total of 16 bytes with the flags at $7F00)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.segment "HEADER"
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.byte $4E,$45,$53,$1A ; 4 bytes with the characters 'N','E','S','\n'
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.byte $02 ; How many 16KB of PRG-ROM we'll use (=32KB)
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.byte $01 ; How many 8KB of CHR-ROM we'll use (=8KB)
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.byte %00000000 ; Horz mirroring, no battery, mapper 0
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.byte %00000000 ; mapper 0, playchoice, NES 2.0
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.byte $00 ; No PRG-RAM
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.byte $00 ; NTSC TV format
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.byte $00 ; Extra flags for TV format and PRG-RAM
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.byte $00,$00,$00,$00,$00 ; Unused padding to complete 16 bytes of header
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; PRG-ROM code located at $8000
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.segment "CODE"
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Reset handler (called when the NES resets or powers on)
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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Reset:
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sei ; Disable all IRQ interrupts
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cld ; Clear decimal mode (not supported by the NES)
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ldx #$FF
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txs ; Initialize the stack pointer at address $FF
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inx ; Increment X, causing a rolloff from $FF to $00
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stx PPU_CTRL ; disable NMI
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stx PPU_MASK ; disable rendering
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stx $4010 ; disable DMC IRQs
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lda #$40
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sta $4017 ; disable APU frame IRQ
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Wait1stVBlank:
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bit PPU_STATUS
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bpl Wait1stVBlank
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txa ; A = 0
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ClearRAM:
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sta $0000,x ; Zero RAM addresses from $0000 to $00FF
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sta $0100,x ; Zero RAM addresses from $0100 to $01FF
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sta $0200,x ; Zero RAM addresses from $0200 to $02FF
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sta $0300,x ; Zero RAM addresses from $0300 to $03FF
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sta $0400,x ; Zero RAM addresses from $0400 to $04FF
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sta $0500,x ; Zero RAM addresses from $0500 to $05FF
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sta $0600,x ; Zero RAM addresses from $0600 to $06FF
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sta $0700,x ; Zero RAM addresses from $0700 to $07FF
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inx
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bne ClearRAM
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Wait2ndVBlank:
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bit PPU_STATUS
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bpl Wait2ndVBlank ; bit-7 is 1
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Main:
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ldx #$3F
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stx PPU_ADDR
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ldx #$00
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stx PPU_ADDR
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lda #$25
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sta PPU_DATA
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lda %00011110
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sta PPU_MASK
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LoopForever:
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jmp LoopForever
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; NMI interrupt handler
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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NMI:
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rti ; Return from interrupt
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; IRQ interrupt handler
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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IRQ:
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rti ; Return from interrupt
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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;; Vectors with the addresses of the handlers that we always add at $FFFA
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;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;;
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.segment "VECTORS"
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.word NMI ; Address (2 bytes) of the NMI handler
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.word Reset ; Address (2 bytes) of the Reset handler
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.word IRQ ; Address (2 bytes) of the IRQ handler
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16
helloppu/nes.cfg
Executable file
16
helloppu/nes.cfg
Executable file
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MEMORY {
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ZP: start = $0000, size = $0100, type = rw, file = "";
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OAM: start = $0200, size = $0100, type = rw, file = "";
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RAM: start = $0300, size = $0500, type = rw, file = "";
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HDR: start = $7FF0, size = $0010, type = ro, file = %O, fill = yes, fillval = $00;
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PRG: start = $8000, size = $8000, type = ro, file = %O, fill = yes, fillval = $00;
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CHR: start = $0000, size = $2000, type = ro, file = %O, fill = yes, fillval = $00;
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}
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SEGMENTS {
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ZEROPAGE: load = ZP, type = zp;
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HEADER: load = HDR, type = ro;
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CODE: load = PRG, type = ro, start = $8000;
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CHARS: load = CHR, type = ro, optional = yes;
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VECTORS: load = PRG, type = ro, start = $FFFA;
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}
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1
nes.cfg
1
nes.cfg
@ -7,6 +7,7 @@ MEMORY {
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CHR: start = $0000, size = $2000, type = ro, file = %O, fill = yes, fillval = $00;
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CHR: start = $0000, size = $2000, type = ro, file = %O, fill = yes, fillval = $00;
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}
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}
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SEGMENTS {
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SEGMENTS {
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ZEROPAGE: load = ZP, type = zp;
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ZEROPAGE: load = ZP, type = zp;
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HEADER: load = HDR, type = ro;
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HEADER: load = HDR, type = ro;
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