11
STAR*TECH JOURNAL/JUNE 1982
SWITCH ES/OPTIONS
The control panel has eight switches mounted on it. These
include the one- and two-player start switches, left and right
pump switches, and a "new" four-way joystick. All inputs from
these switches enter a custom chip at position 1/2 Eon the logic
board. The action of these and the coin switches can be checked
during self test. An especially helpful section on maintaining,
testing and replacing the leaf switches under the joystick, and the
LED switches on the control panel, is located in the "Dig Dug"
game manual, pages 3-11 to 3-15.
The option switches for "Dig Dug" are located on the logic
board at positions 2C/D and 2C. A large number of options are
available affecting pricing, bonus levels and game difficulty, to
name a few. There is also an option switch which will freeze
game operation to aid in troubleshooting the logic board. Careful
examination of the options available will insure maximum
player appeal and operator profitability. For a complete descrip-
tion of all options, see "Dig Dug" game manual, pages 1-9 and
1-10.
BOARD SET
Like most Atari videos there is only a single main logic board
and an audio regulator board in "Dig Dug". As mentioned
earlier, this logic system is built around three Z80A micro-
processors. In addition to the normal audio, sync and color
proms, there are also quite a few "custom" chips on this logic
board. These custom chips include bus controllers, coin and IO
controllers, and a steering controller. The CPUs, program
proms and custom chips are all in sockets for easy substitution
when troubleshooting. The board itself, while made up of many
new components, is made to the same quality standards as
previous Atari boards. Unfortunately, this board has no connector
for the Atari Ram/Rom box or the C.A.T. box. However, an
adaptor to attach to one of the Z80A microprocessors will
probably be available in the near future.
The audio regulator used in "Dig Dug" is the same audio
regulator used since "Missile Command". However, as you
may have noticed in the power distribution section, this system
runs on +5 and+ 10. 3 volts. The regulator/ audio II has circuitry
built on it to supply+ 12 volts,+ 15 volts, and +22 volts. There
is additional circuitry for -15 volts, and -5 volts. Since none of
these voltages are necessary in "Dig Dug", Atari has built the
audio regulator board without these components. What does all
this mean? It means an audio regulator board from a "Missile
Command", Tempest", or "Centipede" will work in a "Dig
Dug", but a "Dig Dug" audio regulator will not work elsewhere.
Additionally, this is just one more board to be stocked by your
local distributor.
SELF TEST
The test switch is located on a utility panel located just behind
the upper coin book. This utility panel also has a coin cQunter,
volume control, and service switch mounted on it. The built in
self test can be used to check memory devices and option settings
on the logic board, all control panel and coin switches, and can
also verify all 21 different sounds produced by the logic board.
There is also a white cross hatch pattern which can be generated
during self test to check monitor convergence. For more
complete details on self test and the procedures required to reset
the high score table, see the "Dig Dug" game manual.
AUDIO SYSTEM
All game sounds originate on the logic board. These various
sounds are summed together and partially amplified by an
LM324 at position 3D/E on the logic board. The outputs of the
LM324 are then connected to the audio regulator board where
they are amplified by two TDA/2002 audio amplifiers. The final
amplified signal is driven through a volume pot to the speaker.
Take note that the same voltage is used by the LM324 on the
logic board and the TDA2002s on the audio regulator board.
(See system power.)
AUDIO SYSTEM
LOGIC
BOARD
REGULATOR/
AUDIO II PCB
SPEAKER
VOLUMEPOT-50-ohm 12½W wirewound
SPEAKER - 6 x 9 inch 4-ohm 15W oval
VOLUME
POT
CONCLUSION
While "Dig Dug" was not originally designed by Atari, it has
been successfully adapted to the Atari system. In fact, this game
is probably one of the most basic videos from an overall game
view Atari has ever manufactured. The logic board operates
primarily on a single voltage ( 5 volts) and the monitor is a
standard Electrohome color model. The usual thorough Atari
game manual with detailed descriptions of game play, self test,
and cabinet assemblies is especially helpful. Without an X-Y
monitor and with no trac-ball assembly, failures in "Dig Dug"
should be quite low, even by Atari's own high standards.