(mirrored from www.gamearchive.com)

The Sega Color X-Y Convert-a-Game System

The System

 Each Sega color X-Y Convert-a-Game system consisted of what is known as the G-80 system. It contains the following elements:

CPU board
Sound board(s)
X-Y Timing and control boards
48K EPROM board

These boards are about the size of a piece of paper (approximately 8 1/2"x11") with one narrow end having an 86 (2x43) pin edge connector. All these boards fit into a card cage, with the individual boards plugging into a interconnect board at the bottom of the cage. The interconnect board allows the boards to be plugged into the slots in any order or position. This board is supplied with voltage from the power supply, and is how all boards are powered. It also acts as a bus to get information between cards.


CPU boards

 The CPU board itself is generic between the X-Y games. However, each game had a special chip (protection chip/slapstick) at U21 and an EPROM at U25 that was specific for that game (the only exception here may be Space Fury and Eliminator). Some games have the same special chip as other games.

These are a list of which special chips go with which games:

Special chip (U21) EPROM (U25) Game
315-0076 1390 Eliminator 4-player
315-0076 1711 Tac/Scan
315-0064 969 Space Fury
315-0064 1873 Star Trek
315-0063 959 Space Odyssey (Version 1 & 2) (non X-Y)
315-0070 969 Eliminator 2-player upright
315-0070 969 Eliminator cocktail
315-0070 1346 005 (non X-Y)
315-0062 829 Astro Blaster (non X-Y)
315-0082 1778 Monster Bash (non X-Y)
315-0082 1611 Zektor

X-Y timing and control boards

 These boards, often referred to as the X-Y pair, are the boards that control the monitor. They are generic between all X-Y games. These boards are hooked together via ribbon cable.

Sound boards

 There is some compatibility of sound boards between games. There may or may not be necessary EPROM swaps on some of these boards.

Sound board Games used with
Battle Star Space Fury
Meatball/Eliminator Eliminator 2-player
Meatball/Eliminator
Eliminator 4-player
Universal Tac/Scan
Universal
Star Trek
Sound board Zektor
Speech board Space Fury
Speech board
Star Trek
Speech board
Zektor

Meatball and Eliminator sound boards are the same; apparently Sega changed the name of this sound board during production of the game. According to schematics, the sound board for Zektor is virtually the same as Eliminator's. However, the part numbers are different on the schematics pages, so their may be a slight difference between the two that I did not spot.

Both Battlestar and Meatball/Eliminator sound boards both have a large socket on them. It is ok that they are unpopulated. I found a SOUND AY-3-8912 in a Battlestar sound board once, and it shows up on the schematic, but removing the chip seems to have no effect.

Speech boards have very little circuitry on them, so don't get worried if you pickup a set and see that the speech board is barely populated. I have seen several speech board sets whose EPROM numbers are not continuous. For example, Space Fury's speech board has EPROMs 970-972, and 808. The 808 is a 2716, while the others are 2732s. I would speculate that the 808's were from Astro Blaster. However, these leftover EPROMS ARE NECESSARY for the speech boards to run correctly. Star Trek uses a Zektor EPROM for its speech board.


EPROM boards

 The EPROM boards are generic between games; any set of Sega/Gremlin X-Y EPROMs can be put into any G-80 EPROM board.

Schematics for much of the above can be found on the Wiretap Arcade Game Simulation pages.

 

Prepared by Ian Boffin
Last updated March 12, 2002