Star Tech Journal

12
STAR*TECH JOURNAL/JULY 1982
Self Test
The video-pinball interface test is designed to check ROM and RAM
devices as well as communication lines to and from the video card cage.
Complete instructions for this test are located in Production
"Caveman" manuals. Game manuals for sample games are incomplete
and should be replaced.
Monitor
The monitor used in "Caveman" is a 13-inch Electrohome Model No.
G07- l 3". Instructions for removal of the monitor from the game cabinet
are found in the game manual.
Video/Pinball Communications
The most interesting aspect of " Caveman" is the method used to
establish communication lines between the pinball and video games
systems. As can be seen in Diagram 2, all data is transferred via the
A23J2 connector. This includes lamp data from the driver board to the
video game; and switch matrix information from the video game to the
control board.
The same outputs which are normally used to drive controlled lamps
on the pinball playfield are sent as inputs to the video game. Since these
lamp driver transistors are controlled by the pinball processor, they can
be used to output a code to the video game to tell it what's going on. The
information is transmitted in the form of a four-bit binary code. Lamps 4,
5, 6, and 7 output a code determining which player is up, while lamps 12,
13, 14, and 15, with lamp 16 used as a data strobe, send out game status
flags. The chart below offers some true examples of these codes:
Meaning
Code
L7
0
0
0
1
L6
0
0
1
0
L5
0
1
0
0
L4
1
0
0
0
Player
Player
Player
Player
L15
0
0
0
L14
0
1
1
L13
1
1
1
L12
0
0
1
Enter video play (left)
Enter extra ball object on screen
Tilt
1 up
2 up
3 up
4 up
This is the method used by the pinball game to communicate to the video
game, but how does the video communicate to the pinball? The normal
lines of communication to a pinball system are through the switch
matrix, and this is exactly how it is done. Switch strobes are sent to the
video game and are sent back via returns 0 through 6 for strobe 0, and
return O through 5 for strobe 1. When playing the video game and the
player crushes a brontosaurus, to the pinball MPU this is just like a
switch on the playfield being closed. It receives information on the
switch matrix and reacts by putting up the correct amount of points and
turning on the appropriate audio. The following chart lists some true
examples of how this works:
Strobe
Return
0
0
0
0
3
5
1
1
Meaning
Brontosaurus or Triceratop crushed
Award extra ball
Last Brontosaurus crushed
Caveman is moving (sound)
The examples shown in the lamp data and switch matrix charts are only
partial listings. For a complete listing, see the " Caveman" Production
Game Manual (video-pinball interface test). This section will have
complete charts plus instructions for an outstanding self test feature for
checking all communications lines.
Please take note that the normally closed slam switch on the front
door is connected via A23J2 pin 24 to the NMI input on the
microprocessor.
Conclusion
While " Caveman" is essentially two games in one, it would seem that
repairs should be twice as difficult. This is not the case, however. Based
on the recent improvements in reliability of "Devil's Dare" and
"Haunted House" ( in deference to the vertical upkicker), there is no
reason to think that the single ball, single layer playfield pinball section
of "Caveman" should be anything but reliable. The reliability of the
video section is a wait and see prospect, although very few failures have
occurred to date. The most unfortunate aspect is that if the video section
fails, it cannot be removed to leave just the pinball section operating.
With the video cage disconnected, the pinball will power up normally,
but credits cannot be added and no games can be started. Also, self test
cannot be initiated.
DIAGRAM 2
Joystick
NOTES
1. Joystick - 4-way Wico
2. A23J2 connector
located on 1/0 board.
3. A18J3 connector
located on video 2 board.
4. A 16J 1 connector
located on card cage.
A23J2
Driver
Board
Lamp Data
Out
Video
Card
Cage
Monitor
Sync and
Video
Out
Control
Board
C\I
-,
Switch
Matrix
Info
C')
C\I
<(
+Svdc Reg.
(Bottom Board)
Connector
Connector
A23J2
A16J1
Pin 2 - Joystick Down
Pin 4- +5vdc
Pin 3 - Joystick Up
Pin 5- +5vdc
Pin 10 - Ground Pin 4 - Joystick Left
Pin 11 - Ground Pin 5 - Joystick Right
Pin 6 - Lamp 7 Data
Pin 7 - Lamp 6 Data
Connector
Pin 8 - Lamp 5 Data
A18J3
Pin 9 - Lamp 4 Data
Pin 1 - Ground
Pin 10- Lamp 16 Data
Pin 3- Red
Pin 11 - Lamp 15 Data
Pin 4-Green
Pin 12- Lamp 14 Data
Pin 5- Blue
Pin 13- Lamp 13 Data
Pin 6- Sync
Pin 14 - Lamp 12 Data
Pin 15 - Return 6
Pin 16 - Return 5
Pin 17 - Return 4
Pin 18 - Return 3
Pin 19 - Return 2
Pin 20 - Return 1
Pin 21 - Return 0
Pin 22 - Strobe 1
Pin 23 - Strobe 0
Pin 24-Slam