Advertisement
-L
osc
or
-DLY
osc
+L
osc.
~ll's--l
D
D O D
D
o
D
D O
D O
o
I
or
+DLY
osc.
PI
1 0 0 0
DO
D O
DO
D O
o
P2
P3
P4
Tl
T2
1500 ns.
.-----z.--
Set on By Mach. Reset Key
1
1
1
r-I ---'1
--cJ.---2S0
ns •
0
0
\---11'5
----l
D
0
0
r
o
o
o
D
D
0
T3
o
D
0
D
0
0
T4
o
Figure 2-14.
Developing Clock
Pulses
D
As can be seen from Figure 2-14,
clock latch 1 is turned on by clock-
start, DIy Osc, not-clock-3, and
clock-4.
The initial turn-on of clock-4
is by clock-reset, which is initiated by
either the machine-reset switch, or by
power turn-on reset circuits.
Clock
latches
1,
2, and 3 turn off with the
initial turn on of clock-4, so that
normal progression of clock latches can
be turned on.
When the clock-start line
is activated and the - DIy Osc becomes
plus, clock-l will turn on.
Figure 2-15 shows the relationship of
the turn-on and turn-off of the clock
latches.
You will note that the lines
+
Dly Osc and - Dly Osc are not shown on
the timing chart.
They are essentially
the same as the
+
esc and - Osc lines
and are used in the same manner to turn
on and turn off the .clock latches.
This
timing chart shows that all clock
latches are on for 500 nanoseconds and
that they successively overlap each
other.
Clock-1 is latched eN with the
positive-going -Dly Osc pulse.
On the
2-6
D
0
D
0
following plus shift of the
+
Dly esc
line, clock-2 turns on.
The second plus
shift of - Dly Osc and the fact that
clock-2 is on, resets the clock-1 latch.
The binary-connected latches continue in
this manner, and as shown in Figure 2-14
and 2-15, form separate and distinct
pulses.
CLOCK
DISTRIBUTION
The clock serves as a central source of
four clock pulses which are put on four
transmission lines.
The transmission
lines deliver the pulses to subdistribu-
tion points throughout the machine.
At
thesesubdistribution points, line-sense
amplifiers tap off from the transmission
line and feed a tWO-input, 30-nanosecond
AOI.
This brings together two clock
pulses to form one timing pulse.
For
example, P1 and P4 are switched to
develop T1.
These pulses are then pow-
ered and used by the decision blocks as
their basic timing pulses.
Advertisement
