SIT board

Picture by User:Hpman

Extension board for the trackball used with The Irritating Maze. Connects to the JAMMA edge, to the output port, and to the various boards used by the game (for lights, air compressor, ticket mechanism...).

The outputs are organized as:

• 16 2A sink outputs made with D1764 60V NPN Darlington transistors (only 11 populated).
• 8 500mA sink outputs made with a 2083 Darlington array through resistors.

The 24V input is only used for the discrete flyback diodes on the 2A transistors.

The inputs from the MV1B go through a HC14 inverter except one (reset ?) before going to the EPM7128 CPLD (the same used in Metal Slug X - Super Vehicle-001) which contains at least 2 quadrature decoders and counters, one 16bit SIPO register with latch (and maybe another 8bit one ?).

Communication

Bit	7	6	5	4	3	2	1	0
Def	Unused		Air jet	Card dispenser ?	Latch	Clock	Data	Trackball X/Y

Special BIOS:

Routine at 1B212: clear outputs 8,0, x16 (32 writes, latch all outputs low)

Routine at 1B322: Read trackball X

Routine at 1B342: Read trackball Y

Dipswitch 2 ON = Card dispenser connected

1B5C2: Air jet

Routine at 1B494: Set outputs

ROM:0001B494 sub_1B494:
ROM:0001B494                 moveq   #0,d7           ; D7=0
ROM:0001B496                 tst.b   $B22(a5)        ; 0/1/FF (10FE22) FLASH LAMP
ROM:0001B49A                 bne.w   loc_1B4A2       ; If $B22(a5)=0, D7 |= $4000                   0a00 0000 0000 0000
ROM:0001B49E                 bset    #$E,d7
ROM:0001B4A2
ROM:0001B4A2 loc_1B4A2:
ROM:0001B4A2                 move.b  $B21(a5),d0     ; 000000xx COLOR LAMP
ROM:0001B4A6                 beq.w   loc_1B4B2
ROM:0001B4AA                 ror.w   #4,d0
ROM:0001B4AC                 andi.w  #$3000,d0
ROM:0001B4B0                 or.w    d0,d7           ; If $B21(a5)>0, D7 |= ($B21(a5)<<12 & $3000)  0abb 0000 0000 0000
ROM:0001B4B2
ROM:0001B4B2 loc_1B4B2:
ROM:0001B4B2                 tst.b   $B20(a5)        ; 0/1/FF SIDE LAMP
ROM:0001B4B6                 beq.w   loc_1B4BE
ROM:0001B4BA                 bset    #$B,d7          ; If $B20(a5)>0, D7 |= $0800                   0abb c000 0000 0000
ROM:0001B4BE
ROM:0001B4BE loc_1B4BE:
ROM:0001B4BE                 tst.b   $B1F(a5)        ; 0/1/FF TRACK BALL LAMP
ROM:0001B4C2                 beq.w   loc_1B4CA
ROM:0001B4C6                 bset    #$A,d7          ; If $B1F(a5)>0, D7 |= $0400                   0abb cd00 0000 0000
ROM:0001B4CA
ROM:0001B4CA loc_1B4CA:
ROM:0001B4CA                 move.w  $B1C(a5),d0     ; 000000xx xxxxxxxx TIMER LAMP
ROM:0001B4CE                 andi.w  #$3FF,d0
ROM:0001B4D2                 or.w    d0,d7           ; D7 |= ($B1C(a5) & $3FF)                      0abb cdee eeee eeee
ROM:0001B4D4                 tst.b   $B29(a5)        ; 0/1/FF
ROM:0001B4D8                 beq.w   loc_1B4E0
ROM:0001B4DC                 bset    #$F,d7          ; If $B29(a5)>0, D7 |= $8000                   fabb cdee eeee eeee
ROM:0001B4E0
ROM:0001B4E0 loc_1B4E0:
ROM:0001B4E0                 move.b  $B23(a5),d0     ; Mirror of $380001
ROM:0001B4E4                 moveq   #$F,d1          ; 16 bits
ROM:0001B4E6
ROM:0001B4E6 loc_1B4E6:
ROM:0001B4E6                 andi.b  #$31,d0         ; 00xx000x
ROM:0001B4EA                 lsr.l   #1,d7
ROM:0001B4EC                 bcc.w   loc_1B4F4
ROM:0001B4F0                 bset    #1,d0           ; 00xx00dx
ROM:0001B4F4
ROM:0001B4F4 loc_1B4F4:
ROM:0001B4F4                 move.b  d0,($380001).l  ; Data set
ROM:0001B4FA                 nop
ROM:0001B4FC                 nop
ROM:0001B4FE                 bset    #2,d0           ; 00xx01dx
ROM:0001B502                 move.b  d0,($380001).l  ; Clock
ROM:0001B508                 dbf     d1,loc_1B4E6
ROM:0001B50C                 nop
ROM:0001B50E                 nop
ROM:0001B510                 andi.b  #$31,d0
ROM:0001B514                 bset    #1,d0
ROM:0001B518                 move.b  d0,($380001).l  ; 00xx001x
ROM:0001B51E                 nop
ROM:0001B520                 nop
ROM:0001B522                 bset    #3,d0           ; 00xx101x
ROM:0001B526                 move.b  d0,($380001).l  ; Latch
ROM:0001B52C                 nop
ROM:0001B52E                 nop
ROM:0001B530                 andi.b  #$31,d0         ; 00xx000x
ROM:0001B534                 move.b  d0,($380001).l
ROM:0001B53A                 rts