Rally X Midway, 9 January 1981
------------------------------
Logic Board I, part. no. A08291385C000
PARTS SIDE | SOLDER SIDE
--------------------------------------------------
(+5V) Gnd | A | 1 | Gnd (+5V)
(+5V) Gnd | B | 2 | Gnd (+5V)
+5V | C | 3 | +5V
+5V | D | 4 | +5V
(?) Credit Mult. | E | 5 | Power Credit Mult. (?)
(Not Used) | F | 6 | Coin Meter
Coin Sw. | H | 7 | NC (?)*
1P Start | J | 8 | 2P Start
P1 Up | K | 9 | P2 Up
P1 Down | L | 10| P2 Down
P1 Right | M | 11| P2 Right
P1 Left | N | 12| P2 Left
P1 Smoke | P | 13| P2 Smoke
Credit Sw. | R | 14| Test Pos.
| S | 15| Gnd (Cocktail only)
(Common) Gnd | T | 16| Gnd (Monitor)
Red | U | 17| Green
Blue | V | 18| Comp. Sync
Spkr | W | 19| Spkr
+12V | X | 20| +12V
(+12V) Gnd | Y | 21| Gnd (+12V)
(+12V) Gnd | Z | 22| Gnd (+12V)
* NC may *not* mean "No Care" for this pinout. I can't figure out what it
does exactly, but it does have traces in the schematic similar to the other
buttons, controls, and switches. Elsewhere on the schematic (pin F) there
is a "N.C." which is, I'm sure, a "No Care" pin.
I have a clone board which has 2 boards connected by 2 IDC cables.
My board has two sets of DIP switches, an 8 way at 11E on the
video/sound board, and 4 way on the CPU board.
Position Option
-------- ------
8 7 6 5 4 3 2 1
-------------------------------
off off *1 coin for 1 play
off on 1 coin for 2 plays
on off 2 coins for 1 play
on on Free play
off off off off 3 cars, rank C, bonus @ 60000
off off off on 2 cars, rank B, bonus @ 40000
off off on off 1 cars, rank C, bonus @ 30000
off off on on 3 cars, rank A, bonus @ 60000
off on off off 2 cars, rank C, bonus @ 40000
off on off on 1 cars, rank B, bonus @ 30000
off on on off 3 cars, rank B, bonus @ 60000
off on on on 2 cars, rank A, bonus @ 40000
on off off off 3 cars, rank C, bonus @ 20000
on off off on 2 cars, rank B, bonus @ 15000
on off on off 1 cars, rank C, bonus @ 10000
on off on on *3 cars, rank A, bonus @ 20000
on on off off 2 cars, rank C, bonus @ 15000
on on off on 1 cars, rank B, bonus @ 10000
on on on off 3 cars, rank B, bonus @ 20000
on on on on 2 cars, rank A, bonus @ 15000
off MAINTENANCE USE ONLY
* indicates default setting
'Switch 8 is for maintenance use only and should normally be in OFF
position. This halts the microprocessor. If it is inadvertently
placed in the ON position, a multicoloured pattern appears on the
screen on power up.'
I've no idea what switch 7 does.
The manual also advises:
'Toggle switches are also found at position 4A on the CPU board. These
are for maintenance only and should not be touched.'
Looking at the circuit diagram, we see that:
Switch1: No connection
Switch2: on: pin 21 of ROMS tied to A12 line.
Off: pin 21 of ROMS isolated
Switch3: on: 'A' input of '139 ROM decoder tied to A12 line.
Off: 'A' input of '139 ROM decoder tied high.
: on: pin 21 of ROMS tied to +5V
Off: pin 21 isolated
My guess is that they select 2716 or 2732 ROMS.
2716: switch 3,4 on, switch 2 off
2732: switch 3,4 off, switch 2 on
I have 2716's on my board, and mine are set as shown.