Star Tech Journal

STAR*TECH JOURNAL/JUNE 1983
16
ANALYZING THE
DATA EAST
CASSETTE SYSTEM (PART 1)
By David B. Mariant, Data East USA, Inc., Santa Clara, CA
The game program is stored on the micro cassette
tape and, for security reasons, the key module is the
data descrambler. The following games are available
for the casette system: Bump 'N' Jump, Burgertime,
Mission-X, Explorer, Lock 'N' Chase, Super Astro
Fighter, Astro Fantasia, Disco No. 1, Pro Golf,
Terranean, Nebula, and Manhattan.
Data East has 7 5 design engineers. New games for
the cassette system will be released at the rate of one
new game every two months. The Data East Cassette
System was first released in the U.S. market about two
years ago. Due to the market change and the recent
success ofBurgertime and Bump 'N' Jump, the Data
East Cassette System will become a known face in the
marketplace.
MICROCASSETTE TAPE
KEY MODULE
The Data East Cassette System is an interchangeable
video arcade game. The idea is relatively simple: By
changing a micro cassette tape (see photo) and key
module (see photo) you can have a new game.
SYSTEM INTERCONNECT {FIGURE 1)
The board set for the cassette system consists of three printed
circuit boards. The printed circuit boards are connected via a
100-pin parallel bus. The mother board has four 100-pin
slots, but only three are used. The fourth slot is used for
factory testing and possible future expansion. To date, Data
East has had two versions of the cassette system PCBs. The
first version was produced up until September 1982. At that
point, the second version was put into effect. The theory of
operation for both versions is the same, however the hardware
layout has been rearranged, and the board size has been
reduced. The Version No. 1 printed circuit boards are RMS-
3, DSP-3, and BI0-3. The Version No. 2 printed circuit
boards are RMS-8, DSP-8, and BI0-8. This article will be
referring to the Version No. 2 PCBs.
SWITCHING
REGULATOR
+5v
-5v
+12v
DSP-8
SPEAKER
C
a:
<
C
a,
a:
w
:c
RMS-8
TO MONITOR
I-
a
::i:
B1O-8
TAPE
DECK
I - - - - - - - + TO KEY MODULE
TO CONTROL PANEL
FIGURE 1
BOARD SET
RMS-8 Dynamic RAM & Sound Control
1. Dynamic Memory (Total 48k Bytes)
A) Program - 24k Bytes
B) Display - 24k Bytes
DSP-8 Timing & Processor
1. CPU Control & Related Parts
A) Processor - 6502 (Custom)
B) CPU Clock- .75MHz
2. Sound Control
A)CPU - 6502
B) ROM - 2k/4k Boot-Strap
C) RAM - 4K Sound Program
D) Sound Chips - 2 G.I. Programmable
Sound Chips
E) Amp/Mixing - 4-Watt Amp & Sound
2. Color Signal Generator and Control
A) DI A Converter - 15 colors out of 236
possible
B) Color Control RAM - 4 chips@ 16x4
bits
C) Priority Color Selector - 4 lines each. 4
inputs and I output
D) Line Buff Control- Hold current line to
be edited @ H BLK • time
Mixing
F) Communications with main CPU via 8-
bit latches
3. Reset Signal Generator
A) Reset In/Reset Out (active low)
4. Dipswitches
A) Dipswitch #I: Controls coins per play
and type of machine.
B) Dipswitch #2: Controls game play,
number oflives, difficulty and movements.
5. System Boot-Strap ROM
A) 4k Book Strap (Load tape contents to
RAM)
3. Standard Pattern Generator and Timing
Signals
A) Base Clock - 12.0 MHz
B) Dynamic RAM Timing - RAS, CAS,
and MUX lines
C) Strobe Signals - Such as write strobe to
RAMs
4. CRT Timing Signals Generator
A) Horizontal Display Counter - 9 bit
(Disp.: OOH-FFH, Blank: I OOH-l 7FH)
B) Vertical Display Counter - 9 bit (Disp.:
08H-FFH, Blank: fESH-IFFH)
C) Synchronization - Horizontal, Vertical,
Neg. Composite out
5. Display Control
A) Missile Generator - 16 missiles in 2
colors
B) Mix Mode Generator- 8 16 dtsxl6 dts
(sprites)
C) Main Graphics Gen. - 1024 8x8 char.
generator type
BI0·8 Background and 1/0
l . Control Panel Switch Input
2. Coin Switch Activation and Coin Counter
Driver
3. NMI Generation from Service Switch/Coin
Switch Activation
4. Volume input AID Conversion
5. Back Display
A) R/W function from CPU to memory
B) Headlight mode
C) Display horizontal/vertical shift
6. Cassette Deck Interface
A) Cassette controller CPU - Transfers to
system CPU