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Different Versions -
Three different versions
of these games exist. The first two use laserdisc technology, the third is based on a 3DO home console. Early systems are
one player only and use a plain
Amiga 500 motherboard, a genlock, a Sony LDP-1450 laserdisc player, a Rev.A RAM
/ ROM board, a sound amplifier board, a single player optoisolator board, and a
light gun. When two players games came in, a partial redesign of the existing
hardware was done. The RAM / ROM board was upgraded to Rev.B, the optoisolator
board was expanded to accept a second gun as input and the sound amplifier board
was integrated into it. The two boards combined were named as TAOS board. A
one player game can be run on a two player setup by using the proper RAM / ROM
board and utilizing the second player gun as the only gun for shooting.
Later versions were built around a Panasonic 3DO system, thus based on CD-ROM technology.
The 3DO systems were slightly modified to be used in a arcade machine, utilizing custom
interfaces (Coyote board) to connect the guns, coin mechs and control
panel inputs to the game system. An example of modification that was done is the
spindle motor replacement. Regular 3DO spindle motors were not designed to run
all day in an arcade environment and used to fail soon, se Panasonic replaced
them with heavy duty ones. The game CD-ROMs used in the arcades are different
from the home versions, so they are not interchangeable. Gameplay is pretty much
the same as the laserdisc versions, but the video quality is inferior.
All the games versions, both
American and European, run on NTSC video format.
The genlock and/or 3DO video outputs are NTSC composite, so the games can be
played on a regular NTSC TV or monitor with composite video input. However, for
arcade use, a standard NTSC demodulator board is used to display the NTSC video
on the arcade monitors (25" and 33" versions). The big screen models use a regular 46" retro-projection
Pioneer TVs mounted inside the cabinet.
Gun Info - For info on the gun
wiring, check the ALG Gun
Wiring Diagram. Most of the guns were black metal guns. Early models needed
an external 'shot amplifier module' between gun and optoisolator board. This
module was later removed with an hardware upgrade of the pcb mounted inside the
gun itself.
Most of the weapons use a mercury switch installed inside their shell to detect
the gun position (horizontal - shooting ; vertical - gun folded, reload
position). WSJR uses a small machine gun, without mercury switch (the game
doesn't support reloading). Space Pirates uses a sort of space laser guns. 3DO
guns are orange plastic guns. Similar guns of the same color were sometimes used
also in the laserdisc version of the games: the guns were lighter, with the same
hardware as metal guns but mounted inside a gun shell marked 'Nintendo'.
Interchangeable -
Most of the games are interchangeable
with minor hardware adjustments with the exception of Fast Draw which uses a vertically
mounted monitor while the other 8 games use a horizontally mounted monitor. To
convert a game into another one, you basically have to change the RAM / ROM board
and the laserdisc inside the laserdisc player. The game laserdiscs were all
manufactured by 3M, one sided and plastic backed,
with audio in English and in many other different languages, like Spanish,
French, Italian, Chinese and Japanese.
RAM / ROM Board -
There are two types
of these boards: Rev. A, the early version, which uses two 27512 EPROMs (64 kB
each) and Rev. B, which uses two 27C1001
or 27C010 EPROMs (128 kB each). In addition to the two EPROMs (U1, U2) which
contain the game code, each RAM / ROM board is equipped with a
zeropower RAM (U3 - MK48Z028-20 or equiv.) and two PAL chips (U4, U5 - PAL16L8).
The idea of the PALs was to scramble the address
lines and the PAL IC surfaces were scraped to prevent illegal reproduction of the
boards. Other than that, the software on the EPROMs isn't encrypted at all, just
scrambled in the addresses. "Mad Dog McCree" had its own scramble (Rev.A),
"Who shot Johnny Rock ?" had its own (Rev.A), but the other games (Rev.B) were all the same. It was too much trouble
to keep coming up with additional board versions. All of the games could run on
the same RAM/ROM board, however, for production, they were run through different
programs to scramble the bits. For more info in this, please visit
the
ALG RAM/ROM info page.
"Mad Dog McCree" and "Who Shot
Johnny Rock?" were the very first games to be developed. They were
designed as a single player game only. The other games are two player games and
required more ROM space because of the amount of software code, so a Rev.B of
the RAM / ROM board with bigger size EPROMs was produced.
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