SIT board
The SIT board is an original extension board designed for The Irritating Maze game. It connects to the JAMMA edge, to the output port (CON1), and to the various peripherals needed by the game (trackball controller, lights, air compressor, ticket dispenser...).
The additional outputs are organized as:
- 11x 2A sink outputs made with D1764 60V NPN Darlington transistors (space for 5 more).
- 8x 500mA sink outputs made with a 2083 Darlington array through resistors.
The 24V input (CON3) is only used for the flyback diodes on the 2A transistors.
The inputs from the MV1B go through a HC14 inverter except one line (reset ?) before going to the EPM7128 CPLD (the same type used in Metal Slug X - Super Vehicle-001) which contains at least 2 quadrature decoders and counters, and one 16 bit SIPO register with latch (and maybe another 8bit one ?).
I/O
The REG_POUTPUT register is used for output control by the special system ROM.
| Bit | 7 | 6 | 5 | 4 | 3 | 2 | 1 | 0 |
| Def | - | Air jet | Card dispenser ? | Latch | Clock | Data | Trackball X/Y select | |
If dipswitch 2 ON: Card dispenser connected
Code
Special system ROM routines:
- $1B212: clear outputs 8,0, x16 (32 writes, latch all outputs low)
- $1B322: Read trackball X
- $1B342: Read trackball Y
- $1B5C2: Air jet
- $1B494: Set outputs:
ROM:0001B494 sub_1B494: ROM:0001B494 moveq #0,d7 ; Start off with D7 cleared 0000 0000 0000 0000 ROM:0001B496 tst.b $B22(a5) ; $10FE22: FLASH LAMP (flag) ROM:0001B49A bne.w loc_1B4A2 ROM:0001B49E bset #$E,d7 ; 0a00 0000 0000 0000 ROM:0001B4A2 ROM:0001B4A2 loc_1B4A2: ROM:0001B4A2 move.b $B21(a5),d0 ; $10FE21: COLOR LAMP (2 bits, 000000xx) ROM:0001B4A6 beq.w loc_1B4B2 ROM:0001B4AA ror.w #4,d0 ROM:0001B4AC andi.w #$3000,d0 ROM:0001B4B0 or.w d0,d7 ; 0abb 0000 0000 0000 ROM:0001B4B2 ROM:0001B4B2 loc_1B4B2: ROM:0001B4B2 tst.b $B20(a5) ; $10FE20: SIDE LAMP (flag) ROM:0001B4B6 beq.w loc_1B4BE ROM:0001B4BA bset #$B,d7 ; 0abb c000 0000 0000 ROM:0001B4BE ROM:0001B4BE loc_1B4BE: ROM:0001B4BE tst.b $B1F(a5) ; $10FE1F: TRACK BALL LAMP (flag) ROM:0001B4C2 beq.w loc_1B4CA ROM:0001B4C6 bset #$A,d7 ; 0abb cd00 0000 0000 ROM:0001B4CA ROM:0001B4CA loc_1B4CA: ROM:0001B4CA move.w $B1C(a5),d0 ; $10FE1C: TIMER LAMP (word, 10 bits, 000000xx xxxxxxxx) ROM:0001B4CE andi.w #$3FF,d0 ROM:0001B4D2 or.w d0,d7 ; 0abb cdee eeee eeee ROM:0001B4D4 tst.b $B29(a5) ; $10FE29: ? (flag) ROM:0001B4D8 beq.w loc_1B4E0 ROM:0001B4DC bset #$F,d7 ; fabb cdee eeee eeee ROM:0001B4E0 ROM:0001B4E0 loc_1B4E0: ROM:0001B4E0 move.b $B23(a5),d0 ; Copy of $380001 ROM:0001B4E4 moveq #$F,d1 ; Shift out 16 bits ROM:0001B4E6 ROM:0001B4E6 loc_1B4E6: ROM:0001B4E6 andi.b #$31,d0 ; Mask out latch, clock and data bits (00xx000x) ROM:0001B4EA lsr.l #1,d7 ROM:0001B4EC bcc.w loc_1B4F4 ROM:0001B4F0 bset #1,d0 ; Set data bit (00xx00dx) ROM:0001B4F4 ROM:0001B4F4 loc_1B4F4: ROM:0001B4F4 move.b d0,($380001).l ; Output data ROM:0001B4FA nop ROM:0001B4FC nop ROM:0001B4FE bset #2,d0 ; 00xx01dx ROM:0001B502 move.b d0,($380001).l ; Set clock high ROM:0001B508 dbf d1,loc_1B4E6 ; Loop for all bits ROM:0001B50C nop ROM:0001B50E nop ROM:0001B510 andi.b #$31,d0 ; Mask out latch, clock and data bits (00xx000x) ROM:0001B514 bset #1,d0 ROM:0001B518 move.b d0,($380001).l ; Set data bit (00xx001x) ROM:0001B51E nop ROM:0001B520 nop ROM:0001B522 bset #3,d0 ROM:0001B526 move.b d0,($380001).l ; Set latch bit (00xx101x) ROM:0001B52C nop ROM:0001B52E nop ROM:0001B530 andi.b #$31,d0 ; Clear (00xx000x) ROM:0001B534 move.b d0,($380001).l ROM:0001B53A rts