Star Tech Journal
Issue: 1984-August - Vol 6 Issue 6 - Page 13
__
Au_a_u_s_T_1_9s_4 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
$TAR-1( IECrl
5514 at SM. It is only a 1 K x 4 bit ROM and is
the non-volatile memory for the high scores. It
is the reason for the batteries used on the
board. This same 5514 is used on Williams'
Stargate and Robotron CPU boards. Other
numbers for this same chip are 6514 and
5114. The CPU runs at 8Mhz and has a
separate crystal from the sound and voice
sections which use the 21.4 7727Mhz crystal.
The RP2A03 can be found in the sound section
of a Donkey Kong 3 board and in double as the
main CPUs on VS. Tennis and VS. Baseball.
The 21.47727Mhz crystal can also be found
on the three above mentioned games. Also,
the main monitor is the lower monitor and has
its signals labeled on all schematics with the
prefix M. The upper monitor, called the screen
monitor, has all its signals prefixed with an S
on the schematic.
The remaining part of this article deals
with the Video board and the BAK board.
The Video board has its own crystal - a
20.16Mhz crystal. This makes a total of three
crystals used on this board. Of course, on
every video game some provision has to be
made for proper horizontal and vertical clock
timing signals, right? Well, this game is no
exception. Except that you remember this:
The CPU (ZS0) is not getting any signal from
the video section other than the VB signal, a
60Hz square wave to interrupt it. This means
that the video section could be totally messed
up and still the main program would operate
properly. This is a real help, because many
other boards (let's say Pac-Man) got their
mainclocksignalfromthevideoclockcircuitry,
and any problem in that clock circuitry means
trouble for the main processor as well. Not so
in this board. The video and main program are
(for the technician) conveniently indepen-
dent, except the VB signal for the CPU, and
I've already told you about that. Who said that
more circuitry meant harder troubleshooting?
It certainly isn't the case with this board,
except the video generating circuitry for the
two monitors. Now that can be difficult! All
kinds of problems could occur here. But most
Nintendo boards are pretty trouble-free. Still,
it helps to know the main operating sections.
There is a common clock section for both
monitors. This is located on the main video
board and uses the chips 2A, 2E, 3A, 3E, 3D,
and 1 D. A problem in this section would most
likely cause problems in both monitors. After
the clock section it is important to remember
that both boards (Video and BAK) use the
DMA0-13 signals from the CPU board as
address signals and the DMD0-7 signals as
the data signals. It is also important to note
that the BAK board is associated with the
generation of background figures of both
monitors and is also the section with the
clearest differentiation of sections - that is,
the circuitry associated with the upper and
lower monitors. I will start with the BAK board.
On this board final color is achieved with 6
PROMs which provide a possible 16 level
intensity for each red, green, and blue color
for each monitor. 7E, SE, and SF are the color
PROMs for the lower monitor(M), and 6E, 6F,
and 7F for the upper monitor. From this point
the sections can be separated by noting
where the address and data lines run. The
drafter who drew the schematic forgot to list
the board locations for several chips, es-
pecially the multiplexer chips that are with the
lower monitor. This makes the schematic more
difficult to use. But here is what the large
EPROMs on this board are responsible for
generating. 4C and 4D are for generating the
images on the S (upper) monitor, and 4A and
4B are for generating the background on the
lower monitor. The 2115 (6116) type RAMs at
3H and 3J are used with the lower monitor
and the 3F (2115) is used with the upper
monitor. Since both upper and lower monitors
are addressed by the same address and data
signals, the ZS0 must have a way of uniquely
addressing either monitor. This is accom-
plished on the BAK board by address lines
DMA 12 and 13 which go to the demultiplexers
at 1 A and 2A The BAK board has two ways of
multiplexing data into the final color PROMs.
Either it selects data in the background cir-
cuitryorcharacterdata via the demultiplexers
directly before the ZS0 itself. On the Video
board it will be sufficient to say what EPROMs
are responsible for what, as this is a compli-
cated board. The challenging boxer's shape
that is displayed on the lower monitor is
contained in8Pand6P. There are 11 27128s,
16K x 8 EPROMs at locations 2U, 2V, 2T, 2R,
3U, 3V, 3T, 3R, 4U, 4T, and 4R. They contain
the opposing boxer's shapes. I hope that with
this information you will be able to figure out
in which section you are having trouble if you
are having a problem. The way we approach
any problem with logic boards where I work is
to dump the EPROM memory onto disk of our
resident computer from a good board and use
this dump to check against a faulty board if we
suspect a problem in that EPROM. This greatly
reduces troubleshooting time for us. Without
those memory dumps on most all the games
we deal with we would have a very serious
problem troubleshooting any board set,
including this one, if we did not have a com-
parison, like a memory dump of that chip, with
which to compare it. Not having a good com·
parison, especially if you suspect a bad
EPROM, will suspend even the best trouble-
shooter in a special hell of guessing what it
might be and not be able to tell if it is a good
memory. If one can eliminate the memory and
the microprocessor as being the cause of the
problem at hand, given enough time, patience
and extra chips, almost any board can be
fixed. I hope you will have the same tools at
your disposal. If you have any questions,
especially about the hint I mentioned earlier
in the article, please call me any time since I
am at my shop a whole lot, not just 8:30 to
5:00. I would like to hear from you. The
number is 501 /753·1148. Sorry it isn't toll
free.
INTERESTED IN ADVERTISING?
S• T J reaches over 4,000 service shops with a
readership of over 12,000 operators, distri-
butors, technicians and manufacturer suppliers.
Your message gets read more than once ...
again and again. For more information call
Paul at 609/662·3432.
~
12 9
Au_a_u_s_T_1_9s_4 _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
$TAR-1( IECrl
5514 at SM. It is only a 1 K x 4 bit ROM and is
the non-volatile memory for the high scores. It
is the reason for the batteries used on the
board. This same 5514 is used on Williams'
Stargate and Robotron CPU boards. Other
numbers for this same chip are 6514 and
5114. The CPU runs at 8Mhz and has a
separate crystal from the sound and voice
sections which use the 21.4 7727Mhz crystal.
The RP2A03 can be found in the sound section
of a Donkey Kong 3 board and in double as the
main CPUs on VS. Tennis and VS. Baseball.
The 21.47727Mhz crystal can also be found
on the three above mentioned games. Also,
the main monitor is the lower monitor and has
its signals labeled on all schematics with the
prefix M. The upper monitor, called the screen
monitor, has all its signals prefixed with an S
on the schematic.
The remaining part of this article deals
with the Video board and the BAK board.
The Video board has its own crystal - a
20.16Mhz crystal. This makes a total of three
crystals used on this board. Of course, on
every video game some provision has to be
made for proper horizontal and vertical clock
timing signals, right? Well, this game is no
exception. Except that you remember this:
The CPU (ZS0) is not getting any signal from
the video section other than the VB signal, a
60Hz square wave to interrupt it. This means
that the video section could be totally messed
up and still the main program would operate
properly. This is a real help, because many
other boards (let's say Pac-Man) got their
mainclocksignalfromthevideoclockcircuitry,
and any problem in that clock circuitry means
trouble for the main processor as well. Not so
in this board. The video and main program are
(for the technician) conveniently indepen-
dent, except the VB signal for the CPU, and
I've already told you about that. Who said that
more circuitry meant harder troubleshooting?
It certainly isn't the case with this board,
except the video generating circuitry for the
two monitors. Now that can be difficult! All
kinds of problems could occur here. But most
Nintendo boards are pretty trouble-free. Still,
it helps to know the main operating sections.
There is a common clock section for both
monitors. This is located on the main video
board and uses the chips 2A, 2E, 3A, 3E, 3D,
and 1 D. A problem in this section would most
likely cause problems in both monitors. After
the clock section it is important to remember
that both boards (Video and BAK) use the
DMA0-13 signals from the CPU board as
address signals and the DMD0-7 signals as
the data signals. It is also important to note
that the BAK board is associated with the
generation of background figures of both
monitors and is also the section with the
clearest differentiation of sections - that is,
the circuitry associated with the upper and
lower monitors. I will start with the BAK board.
On this board final color is achieved with 6
PROMs which provide a possible 16 level
intensity for each red, green, and blue color
for each monitor. 7E, SE, and SF are the color
PROMs for the lower monitor(M), and 6E, 6F,
and 7F for the upper monitor. From this point
the sections can be separated by noting
where the address and data lines run. The
drafter who drew the schematic forgot to list
the board locations for several chips, es-
pecially the multiplexer chips that are with the
lower monitor. This makes the schematic more
difficult to use. But here is what the large
EPROMs on this board are responsible for
generating. 4C and 4D are for generating the
images on the S (upper) monitor, and 4A and
4B are for generating the background on the
lower monitor. The 2115 (6116) type RAMs at
3H and 3J are used with the lower monitor
and the 3F (2115) is used with the upper
monitor. Since both upper and lower monitors
are addressed by the same address and data
signals, the ZS0 must have a way of uniquely
addressing either monitor. This is accom-
plished on the BAK board by address lines
DMA 12 and 13 which go to the demultiplexers
at 1 A and 2A The BAK board has two ways of
multiplexing data into the final color PROMs.
Either it selects data in the background cir-
cuitryorcharacterdata via the demultiplexers
directly before the ZS0 itself. On the Video
board it will be sufficient to say what EPROMs
are responsible for what, as this is a compli-
cated board. The challenging boxer's shape
that is displayed on the lower monitor is
contained in8Pand6P. There are 11 27128s,
16K x 8 EPROMs at locations 2U, 2V, 2T, 2R,
3U, 3V, 3T, 3R, 4U, 4T, and 4R. They contain
the opposing boxer's shapes. I hope that with
this information you will be able to figure out
in which section you are having trouble if you
are having a problem. The way we approach
any problem with logic boards where I work is
to dump the EPROM memory onto disk of our
resident computer from a good board and use
this dump to check against a faulty board if we
suspect a problem in that EPROM. This greatly
reduces troubleshooting time for us. Without
those memory dumps on most all the games
we deal with we would have a very serious
problem troubleshooting any board set,
including this one, if we did not have a com-
parison, like a memory dump of that chip, with
which to compare it. Not having a good com·
parison, especially if you suspect a bad
EPROM, will suspend even the best trouble-
shooter in a special hell of guessing what it
might be and not be able to tell if it is a good
memory. If one can eliminate the memory and
the microprocessor as being the cause of the
problem at hand, given enough time, patience
and extra chips, almost any board can be
fixed. I hope you will have the same tools at
your disposal. If you have any questions,
especially about the hint I mentioned earlier
in the article, please call me any time since I
am at my shop a whole lot, not just 8:30 to
5:00. I would like to hear from you. The
number is 501 /753·1148. Sorry it isn't toll
free.
INTERESTED IN ADVERTISING?
S• T J reaches over 4,000 service shops with a
readership of over 12,000 operators, distri-
butors, technicians and manufacturer suppliers.
Your message gets read more than once ...
again and again. For more information call
Paul at 609/662·3432.
~
12 9
Future scanning projects are planned by the International Arcade Museum Library (IAML).