THE STACK AREA OF MEMORY
    7FFF: ??? already in use
    7FFE: ??? already in use
    7FFD: return address from start to its caller
    7FFC: old fp; start's stack frame starts here
    7FFB: x (uninitialised)
    7FFA: y = 1739
    7FF9: z (uninitialised)
    7FF8: f's base = 10; F's stack frame starts here
    7FF7: f's x = 1736
    7FF6: 040B; return address
    7FF5: 7FFC; old fp
    7FF4: a = 173
    7FF3: b = 6
    7FF2: base = 10; second stack frame for recursive f
    7FF1: x = 173
    7FF0: 0424; return address
    7FEF: 7FF5; old fp
    7FEE: a = 17
    7FED: b = 3
    7FEC: base = 10; third stack frame for f
    7FEB: x = 17
    7FEA: 0424; return address
FP->7FE9: 7FEF; old fp
    7FE8: a = 1
SP->7FE7: b = 7
    7FE6:
    7FE5:

  THE STATIC AREA OF MEMORY
    0400: start: push  fp
    0401:        load  fp, sp
    0402:        sub   sp, 3
    0403:        load  r1, 1739
    0404:        store r1, [fp-2] // y
    0405:        push  10
    0406:        load  r1, [fp-2]
    0407:        sub   r1, 3
    0408:        push  r1
    0409:        call  PC+7    // address of f
    040A:        add   sp, 2   // two params were pushed
    040B:        push  '\n'
    040C:        call  (address of outch)
    040D:        add   sp, 1   // one param was pushed
    040E:        add   sp, 3   // remove local vars
    040F:        pop   fp
    0410:        ret           // pop and jump

    0412: f: push  fp
    0413:    load  fp, sp
    0414:    sub   sp, 2         // two locals
    0415:    load  r1, [fp+2]    // x
    0416:    div   r1, [fp+3]    // base
    0417:    store r1, [fp-1]    //a
    0418:    load  r1, [fp+2]
    0419:    mod   r1, [fp+2]
    041A:    store r1, [fp-2]    // b
    041B:    push  [fp-2]        // say(b)
    041C:    call  (address of say)
    041D:    add   sp, 1
    041E:    load  r1, [fp-1]    // if (a > 0)
    041F:    comp  r1, 0
    0420:    jcond leq, PC+4     // over it
    0421:    push  [fp-1]        // a
    0422:    push  [fp+3]        // base
    0423:    call  PC-18         // f again
    0424:    add   sp, 2
    0425:    push  [fp-2]        // b
    0426:    call  (address of say)
    0427:    add   sp, 1
    0428:    add   sp, 2         // kill two locals
    0429:    pop   fp
    042A:    ret
    042B: 
    042C: