.pc = $801 "Basic"
:BasicUpstart(main)
.pc = $80d "Program"
  .label SCREEN = $400
main: {
    .label j = 3
    .label i = 2
    lda #$64
    sta i
  b1:
    lda #$64
    sta j
  b2:
    jsr nest1
    dec j
    lda j
    bne b2
    dec i
    lda i
    bne b1
    rts
}
nest1: {
    .label i = 4
    lda #$64
    sta i
  b1:
    lda #$64
  b2:
    jsr nest2
    sec
    sbc #1
    cmp #0
    bne b2
    dec i
    lda i
    bne b1
    rts
}
nest2: {
    ldx #$64
  b1:
    ldy #$64
  b2:
    sty SCREEN
    dey
    cpy #0
    bne b2
    dex
    cpx #0
    bne b1
    rts
}
