ORG $1000
START:              ; first instruction of program
    move.w  a,-(sp)     ;push a
    move.w  b,-(sp)     ;push b
    move.l  #x,-(sp)    ;push x
    jsr QUAD
QUAD
    move.w  10(sp),D2   ;pop a
    move.w  8(sp),D3    ;pop b

    move.w  D2,D4       ;START 3*a
    add.w   D2,D4
    add.w   D2,D4       ;END 3*a
    move.w  D4,D1

    cmp.w   #0,D3
    BLT END     ;if 0>b END
    move.w  #0,D5       ;START 2*b
    add.w   D3,D5
    add.w   D3,D5       ;END 2*b
    move.w  D5,D3

END
    move.b  #9,D0
    trap    #15
* Variables and Strings
    org $2000
a   dc.w    2
b   dc.w    36
x   ds.w    1
    END START       ; last line of source