In CPU1 (sound CPU)

00B0: 3E 0E         ld   a,$0E
00B2: 32 80 A0      ld   ($A080),a
00B5: 3A 81 A0      ld   a,($A081)
00B8: 2F            cpl
00B9: 47            ld   b,a
00BA: E6 F0         and  $F0
00BC: 4F            ld   c,a                 IN0 bits 4 to 7 (player 2 controls)
00BD: 78            ld   a,b
00BE: 07            rlca
00BF: 07            rlca
00C0: 07            rlca
00C1: 07            rlca
00C2: E6 F0         and  $F0
00C4: 47            ld   b,a                 IN0 bits 0 to 3 (player 1 controls)
00C5: 3E 0F         ld   a,$0F
00C7: 32 80 A0      ld   ($A080),a
00CA: 3A 81 A0      ld   a,($A081)
00CD: 2F            cpl
00CE: 32 0A 88      ld   ($880A),a
00D1: 5F            ld   e,a
00D2: E6 03         and  $03                 IN1 bits 0 to 1 (player 1 buttons)
00D4: B0            or   b                   merge with player 1 controls
00D5: 32 06 88      ld   ($8806),a           store in shared memory
00D8: 7B            ld   a,e
00D9: 0F            rrca
00DA: 0F            rrca
00DB: E6 03         and  $03                 IN1 bits 2 to 3 (player 2 buttons)
00DD: B1            or   c                   merge with player 2 controls
00DE: 32 07 88      ld   ($8807),a           store in shared memory
00E1: 3E 0E         ld   a,$0E
00E3: 32 90 A0      ld   ($A090),a
00E6: 3A 91 A0      ld   a,($A091)           DSW1
00E9: 2F            cpl
00EA: 32 08 88      ld   ($8808),a           store in shared memory
00ED: 3E 0F         ld   a,$0F
00EF: 32 90 A0      ld   ($A090),a
00F2: 3A 91 A0      ld   a,($A091)           DSW2
00F5: 2F            cpl
00F6: 32 09 88      ld   ($8809),a           store in shared memory
00F9: C9            ret


In CPU0 (main CPU)

062D: 3A 08 88      ld   a,($8808)           load DSW1
0630: E6 10         and  $10                 "Cabinet" Dip Switch
0632: 21 06 88      ld   hl,$8806            use player 1 address
0635: 20 50         jr   nz,$0687            if "Upright", goto Upright
Cocktail :
0637: 3A 4D 80      ld   a,($804D)           player turn
063A: E6 40         and  $40
063C: 28 03         jr   z,$0641             if player 1 goto Read
063E: 21 07 88      ld   hl,$8807            use player 2 address
Read :
0641: 46            ld   b,(hl)              load player controls + buttons
Proceed :
0642: AF            xor  a
...
0670: C9            ret
Upright :
0687: 7E            ld   a,(hl)              load player 1 controls + buttons
0688: 23            inc  hl
0689: B6            or   (hl)                merge player 2 controls + buttons
068A: 47            ld   b,a
068B: C3 42 06      jp   $0642