Nessemble

About Nessemble

Nessemble is a 6502 assembler targeting the Nintendo Entertainment System

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.inesprg 1 .ineschr 1 .inesmap 0 .inesmir 1 ;;;;;;;;;;;;;;;; .rsset $0000 scroll_y .rs 1 ;;;;;;;;;;;;;;;; .prg 0 vblankwait: BIT $2002 BPL vblankwait RTS ;;;;;;;; RESET: SEI CLD LDX #$40 STX $4017 LDX #$FF TXS INX STX $2000 STX $2001 STX $4010 ;;;;;;;; JSR vblankwait ;;;;;;;; clrmem: LDA #$00 STA $0000, X STA $0100, X STA $0300, X STA $0400, X STA $0500, X STA $0600, X STA $0700, X LDA #$FE STA $0200, X INX BNE clrmem ;;;;;;;; JSR vblankwait ;;;;;;;; LoadBackground: LDA $2002 LDA #$20 STA $2006 LDA #$09 STA $2006 LDX #$00 LoadBackgroundLoop: LDA text, X STA $2007 INX CPX #$0D BNE LoadBackgroundLoop ;;;;;;;; LoadPalette: LDA $2002 LDA #$3F STA $2006 LDA #$00 STA $2006 LDX #$00 LoadPaletteLoop: LDA palette, X STA $2007 INX CPX #$20 BNE LoadPaletteLoop ;;;;;;;; LDA #%10000000 STA $2000 LDA #%00011110 STA $2001 ;;;;;;;; LDA #$00 STA <scroll_y ;;;;;;;; Forever: JMP Forever ;;;;;;;; NMI: LDA #$00 STA $2005 INC <scroll_y LDA <scroll_y CMP #$F0 BNE ScrollYDone LDA #$00 STA <scroll_y ScrollYDone: STA $2005 RTI ;;;;;;;; .org $E000 text: .ascii "Hello, World!" palette: .color $000000, $000000, $000000, $000000 .color $000000, $000000, $000000, $000000 .color $000000, $000000, $000000, $000000 .color $000000, $000000, $000000, $000000 .color $FFFFFF, $FFFFFF, $FFFFFF, $FFFFFF .color $FFFFFF, $FFFFFF, $FFFFFF, $FFFFFF .color $FFFFFF, $FFFFFF, $FFFFFF, $FFFFFF .color $FFFFFF, $FFFFFF, $FFFFFF, $FFFFFF ;;;;;;;; .org $FFFA .dw NMI .dw RESET .dw 0 ;;;;;;;;;;;;;;;; .chr 0 .font 0, 127

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