Dice

This program simulates the rolling of 2 dice, 1 on each of the data displays. While the IN button is pressed the dice will roll, when the IN button is released the dice will freeze. The data switches set the size of the dice, for instance if you want to roll one 6-sided and one 8-sided set the data switches to 86h. The high die is cycle balanced and should distribute evenly, the low die is not balanced and will favor 1.

The program is essentially 2 counters. The first counter controls the low die, when it reaches the maximum it will trigger a count on the high counter.

    1 0000:                        org     0
    2 0000: f8 f0                  ldi     0f0h      ; setup temporary storage
    3 0002: a2                     plo     r2
    4 0003: 90                     ghi     r0
    5 0004: b2                     phi     r2
    6 0005: f8 11                  ldi     011h      ; Both dice start at 1
    7 0007: a7                     plo     r7
    8 0008: e2                     sex     r2
    9 0009: 17          loop:      inc     r7        ; increment low die
   10 000a: 87                     glo     r7
   11 000b: fa 0f                  ani     0fh       ; strip high die for compare
   12 000d: 73                     stxd
   13 000e: 6c                     inp     4         ; read switches
   14 000f: fa 0f                  ani     0fh       ; keep only low switches
   15 0011: 60                     irx
   16 0012: f7                     sm                ; see if die is greater than switches
   17 0013: 33 2a                  bdf     good1     ; jump if not
   18 0015: 87                     glo     r7        ; get the high die value
   19 0016: fa f0                  ani     0f0h      ; strip low die value
   20 0018: fc 10                  adi     010h      ; increment high die
   21 001a: 73                     stxd
   22 001b: 6c                     inp     4         ; read switches
   23 001c: fa f0                  ani     0f0h      ; keep only high switches
   24 001e: 60                     irx
   25 001f: f7                     sm                ; see if die is greater than switches
   26 0020: 33 26                  bdf     good2     ; jump if not
   27 0022: f8 11                  ldi     011h      ; reset both dice to 1s
   28 0024: 30 29                  br      save      ; and save result
   29 0026: f0          good2:     ldx               ; recover high die value
   30 0027: f9 01                  ori     1         ; set low die value to 1
   31 0029: a7          save:      plo     r7        ; save result
   32 002a: 3f 09       good1:     bn4     loop      ; see if IN is pressed
   33 002c: 87                     glo     r7        ; if so, then display dice on data displays
   34 002d: 52                     str     r2
   35 002e: 64                     out     4
   36 002f: 22                     dec     r2
   37 0030: 30 09                  br      loop