Fibonacci Sequence in Little Man Computer

fib.asm

        INP
        SUB one
        STA counter
loop    LDA twoLast
        ADD oneLast
        STA next
        OUT
        LDA oneLast
        STA twoLast
        LDA next
        STA oneLast
        LDA counter
        SUB one
        STA counter
        BRP loop
counter DAT 5
twoLast DAT 0
oneLast DAT 1
next    DAT 0
one     DAT 1