Star Tech Journal

S*T J
July 1981
10
WILLIAMS
"DEFENDER 11
SYSTEM
SUMMARY
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There has been an evolution
from the prototype DEFEN-
DER games introduced at
last year's A.M.OA. in
Chicago, to those currently
in production for the U.S.
and Canadian markets, in
both the ROMs used and
Circuit board design. The
changes in ROMs began
with enhanced Self-Test
capabilities and ended with
a program which allows the
same ROMs to be used in
the current upright games
and the soon-to-be avail-
able cocktail table version
of DEFENDER. Changes in
circuit board design was
done for compatability
between upright and cock-
tail table games.
White- and blue-labeled
RO Ms are 10-chip versions;
green- and red-labeled
ROMs are 11-chip versions.
Note that ROM Board
jumper changes are required
when changing a set of
RO Ms between 10- and 11-
chip versions.
The white-labeled ROMs
provided in prototype games
did not have a ROM test
and the RAM test was
incomplete. For this reason,
Williams will exchange a
later version for them. Please
make arrangements with
your Williams Distributor for
this exchange. White-labeled
ROMs can be easily identi-
fied by noting the top
"TODAYS GREATEST" high
score signature. After the
game is first turned on, "DRJ
20000" is indicated with
white-labeled ROMS.
Games with blue-or green-
labeled ROMs do not
display a message for
certain RAM Bank 2 failures.
If there is repeated RAM-
test scanning at power up,
switch Banks 1 and 2 of the
RAMs to isolate a possible
RAM fault. With multiple
RAM failures, only the
lowest RAM number is dis-
played. Faulty decoder
ROM(s) or associated cir-
cuitry can cause a RAM
failure indication. Power up
and reset self tests are
performed solely by ROM
3. Certain failure modes in
ROMs 7, 8, 10, and 11
prevent a ROM failure
message.
In addition to providing
compatibility for upright
and cocktail table games,
red-labeled ROMs retain
the credits in the game after
power down and include
minor program changes for
the cocktail table games.
These changes include re-
setting the "ALL TIME
GREATEST" high score sig-
nature from Special Function
28 only, and providing
more liberal adjustments
for difficulty of game play.
The newly designed CPU/-
Video Board is provided
with two decoder ROMs for
compatibility with cocktail
table games. Note that the
decoder ROM used in the
original board cannot be
used in the latest board.
The newly designed Inter-
face Board can also be used
in either the upright and
cocktail table game. Jumper
W1 on the new Interface
Board must be installed
when the board is used in
an upright game. In
addition, if blue- or green-
labeled ROMs are used,
Jumper W2 must be
removed from upright games.
For cocktail games (red-
labeled ROMs only) Jumper
W1 must be removed and
Jumper W2 be connected.
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