Atari 2600 - Draw colored stripes to screen

stripes.asm

; stripes.asm
;
; Example Atari 2600 program - paints
; colored stripes to the screen
;
; dasm stripes.asm -f3 -ostripes.bin
;
;
    processor 6502

    include "vcs.h"
    include "macro.h"

    SEG

    ORG $F000

Reset:

StartOfFrame:
    lda #0               ; Start of vertical blank processing
    sta VBLANK
    lda #2
    sta VSYNC

    REPEAT 3
       sta WSYNC
    REPEND

    lda #0
    sta VSYNC

    REPEAT 37            ; 37 scanlines of vertical blank...
        sta WSYNC
    REPEND

    ldx #0

    REPEAT 192           ; 192 scanlines of picture...
        inx
        stx COLUBK
        sta WSYNC
    REPEND

Overscan:
    lda #%01000010       ; turn "off" beam
    sta VBLANK           ; end of screen - enter blanking

    REPEAT 30            ; 30 scanlines of overscan...
        sta WSYNC
    REPEND

    jmp StartOfFrame

    ORG $FFFA            ; Cart config (so 6502 can start it up)

    .word Reset          ; NMI
    .word Reset          ; RESET
    .word Reset          ; IRQ

    END