SIT board
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 clamp 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