Atari Super Breakout User Manual

t
4H
A7 pin 13
JS pin 10
JS pin 9
<l>O
r
C3 pin 37
<1>2
r
C3 pin 39
<1>1
L
C3 pin 3
Figure 3-6 Phase 1 and Phase 2 Signal Shaping
4H frequency is generated by the horizontal sync
counter PB, pre-shaped by latch A7, and buffered by
driver JB to produce the <l>O clock input. See Figure
3-7,
Phase 1 and Phase 2 Signal Shaping.
Watchdog RESET
The reset counter in the microprocessor control
circuitry consists of a 4-bit decade counter, C6/7. The
Q
0
output of this counter is the RESE~ signal to the
MPU. Counter C6/7 counts how many times the 12BV
signal
changes states. On every high-to-low transi-
tion of 12BV, the counter advances to the next count
in its sequence. Meanwhile, the TIMER RESET signal,
generated by the MPU at various times during its
normal instruction sequence, is resetting the counter
back to zero. If for some reason the MPU program has
strayed
from its intended instruction sequence and
the TIMER RESET signal does not occur before this
counter counts up to a point where the Q
0
output
goes high, a RESET signal is generated to .th~ MPU.
The RESET signal causes the MPU to restart its instruc-
tion sequence from the beginning of the program.
D. SYNC GENERATOR
(See Figure 3-3, Sheet 1 of 5)
The base frequency of the sync generator is
a
12.096-MHz clock, generated by a crystaJ-
controlled oscillator consisting of crystal Y1, in-
verter N9, and several discrete components.
The output of this oscillator is 12 MHz. Examina-
tion of this signal with an oscilloscope (at pin B
of R9) should show the period (or cycle time) to
be approximately B3 nanoseconds (.OB3 mic-
roseconds). See Figure 3-7.
This base frequency is then divided down
by flip-flop RB and binary counters PB through
NB: it provides the various horizontal syn-
chronization frequencies (1 H through 256H).
The
final output of this horizontal counter chain
is 256H (at pin 11 of NB). This signal is in effect a
division of the base frequency (12.096 MHz) by
76B, to give a horizontal line frequency of 15,750
Hz. The period of 256H is about 63.5 mic-
roseconds. The 256H signal, as well as other
horizontal signals, are used to generate the H
BLANK and H
SYNC timing pulses at flip-flop R1.
See Figure 3-8, Horizontal Sync Timing Diagram
for the relative timing of these waveforms.
The H SYNC
signal is used to clock two
stages of vertical sync counters (l3 and M3). This
H SYNC
signal is divided down by these coun-
ters to form the various vertical synchronization
Super Breakout 3-7

Atari Super Breakout Specifications

General

Brand	Atari
Model	Super Breakout
Category	Video Gaming Accessories
Language	English