Star Tech Journal

13
STAR*TECH JOURNAL/SEPTEMBER 1983
New System Preview continued.
Security Device Test
After the security device goes through its check, it will continuously put out a
33msec clock to the Z80 interrupt. The diagnostics will put itself in a 50msec
delay loop and then check at the end of that loop to see if the security device has
interrupted the Z80. Ifnot, the system will display "68705 Test Failed". If the
interrupt is being generated, the system will go to the sound test.
Sound Test
The sound test outputs a tone scale to each of the three channels of the sound
chip. The user is instructed to check volume control. The sound chip gives no
feedback to the Z80 so the user is given audio feedback. If no sound is heard, the
user should check the AY-3-8910 sound chip. The diagnostics goes to the
display test next.
Display Test
The seven segment displays are cycled through all the digits available. It first
starts with Os and steps through to all 9s. Again no feedback is available to the
Z80 so the user must check to see that the number combinations are okay. The
program next goes to the keyboard check.
Keyboard Test
The keyboard test lasts for 15 seconds. During this 15 seconds the user can push
any key on the keyboard and the corresponding digit will flash a zero on the
seven segment display. The monitor will show which digit corresponds to each
key as shown in the diagram below. After 15 seconds the monitor will display
the colorbar sequence.
Player I Score
I ACTION I RIGHT I
LEFT
DOWN
UP
Pl
COIN I
R2
Pl1
-!il!I--Gw-
~==================~
t::::====:'.::======:::ll~
C2~
74LS04
~
=m :::
Player 2 Score
P2
Circuit Panel Assembly
The circuit panel assembly (PCA board) is the only part of the game ( other than
the monitor boards) that even slightly resembles a logic or CPU board. The
PCA CPU board is a small board by video standards, but handles a large
number of functions. The PCA CPU board is the system controller. It takes the
player's input signals from the control panel and decodes and tells the disc
player what frame to move to. The PCA also drives the score display, produces
the decision beep tone that lets the player know that his next move has been
accepted, recorded and understood by the game, amplifies both channels of
audio coming from the disc player, and carries all of the raw memory on a
piggyback board.
This piggyback board contains five 2764 EPROMs that contain all of the
memory functions necessary to control the disc player and game functions. The
data produced by the PCA is transmitted to the disc player along a 24-pin ribbon
cable that plugs directly into the PCA CPU board and the disc player. There is a
CPU board reset on the PCA that is located on the left side of the board where
the amplifier heat sinks are located. The PCA CPU board is mounted on the
right side of the cabinet when viewed from the rear of the cabinet. The switch is
designated as SW3 below.
<>CZ)
~C54
I COIN 2
HLSOO
Colorbars
The diagnostics will now display colorbars on the monitor. These colorbars will
stay on the monitor until the diagnostics dip switch is turned off. When the
diagnostics switch is turned off, the system will start the game. These colorbars
are used to adjust the video monitor.
S&
C55~
7'LS3 74
s ~
G::)c••
Figure 1: System Power and Block Wiring Diagram
Isolated 115vac
Electrohome
Monitor
Video Input
74LS08 s-i
G::>c••
To Fluorescent
Lamps
115vac
Speaker 1
To Fan
Garn
lnte
AC
~:r::r
Speaker
2
16:Pin
Ribbon
Cable
Video Out
to the Monitor
115vac
Power Supply
The Condor power supply is one of the simplest, most reliable, and easiest to
" work on" systems used in any video today. The +25vdc (unregulated) is used
for the audio amplification circuitry and the +5vdc (regulated via a 723 IC chip
regulator) is the power supply for all logic functions. This unit is really self-
explanatory if you look at Figure 2. Your +5vdc tuning is done using the
variable resistor (trimpot) at point R9.
,,
I
I
I
I
I
I
I
~ "~ii.2~[.
.
:
,,_l
I
,.,•c•-
J
CD
~ . :~
-am--
R38
e
177 ""~::.~~""
Figure 2: Condor Power Supply
80-12035-01
Figure 3-A
Continued on next page.