lda #0
    sta $02
    sta $03                 ;01:  a = 0x0000          ; a = 0
    tay
lp:                         ;02: loop:
    ldx $03                 ;03:  b = a >> 8          ; b = upper byte of address
    lda $6100,x             ;04:  x = mem[0x6100+b]   ; load byte from [0x6100 + b]
                            ;05:  b = a & 0xFF        ; b = lower byte of address
    lda $6200,y             ;06:  x = mem[0x6200+b]   ; load byte from [0x6200 + b]

    lda ($02),y             ;07:  b = mem[a]          ; b = load byte at from mem[a]
    tax
    lda $6300,x             ;08:  x = mem[0x6300+b]   ; load byte from [0x6300 + b]

    iny                     ;09:  a = a + 1           ; increment a
    bne lp                  ;10:  goto loop           ; loop
    inc $03
    bne lp

    beq lp                  ;repeat