Midway 8080 System Boards

The Midway 8080 system board was the basis of many of Midway's black & white video games from 1975 till 1980.
This board is easy to distinguish because of it's shape, The mother board has a daughter board plugged into 
it at a 90 degree angle with 2 aluminum braces holding the boards together. (Midway's Omega Race is very 
similar in appearance but is not part of this system.) The daughter board is used for audio production & 
amplification and input/output interfacing to the cabinet. The mother board has a 8080 cpu, 16 2708 dynamic
Ram chips and 8 sockets for Roms (24 or 28 pin sized). The single edge connector on the mother board is for
power input and video output and is double sided ( component side is electrically the same as solder side).
There is a strapping section on the motherboard to allow for different configurations of ROM chips by
different manufactures. 

The motherboards are nearly functionally identical but come in several basic variations. PC 80-90000-A000
& PC 80-90000-L000 are the last of the series commonly found on Space Invaders, Space Encounters. Revision
L000 has 28 pin EPROM socket setup but is used in the 24 pin configuration. The A000 and L000 revision
boards also have a 7432 chip near the daughter board connector not found on the earlier boards. Earlier
boards I know of are 80-900E, F or H. The layout is slightly different, crystal is in different location
& appears that the ROM jumpers may be different. The motherboards are switch able from game to game but
the daughter board (Audio, I/O port) is unique to each game, some even have a different board for cocktail
vs upright of the same game. Most of the daughter boards can be identified by the circuit board etching
with the game name. Some are not as obvious, who would recognize M4 as a game and not a code? 

Sophisticated for it's day it could produce 224 horizontal lines by 256 blocks.



Space Invaders did not include a RAM test for Midway 8080 boards since it was licsened from Taito and part
of the agreement was no alterations to the code (i.e. test mode).  The Ram Tester P.C. 80-903 can be used
to test the RAMs  (from service bulletin 10/10/78). 

Note that originally the 2716 used on these games were TMS2716's (Texas Instruments) which use 3 voltages
and are not compatible with other 2716's. 



Space Invaders Cocktails 

Game logic boards A084-90700-739 B & C are used in uprights only. 

Game logic boards A084-90700-739 D & E can be used in uprights & table models. All jacks are keyed and will
plug in properly. 

- From Bulletin 3/5/79 



Shuffleboard / Space Invaders PC 0800-09000 H & K Mother boards 

H is strapped for 2716's Only. 
K can be altered for 2716's or 9316's. 

-from Bulletin 10/9/78 



Space Invaders 

Due to a supply problem the 25S10 shifter IC's have been replaced with 74151 Data selector multiplexers. 

PC A084-90700-B000 Have (4) 25S10's 
PC A084-90700-C000 Have (8) 74151's. 

-from Bulletin 12/11/78