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IBM ELECTRONIC MULTIPLIER User Manual page 119

Electric punched card accounting machines

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E L E C T R I C A L
P R I N C I P L E S
115
number of times that the multiplicand counter is
rolled. A group of 10 pulses to roll the multipli-
cand counter is fed to the 10-pulse switch each
adding cycle, but the 10 pulses cannot enter the
multiplicand counter until the 10-pulse switch is
opened by the carry-over of the multiplier counter.
The multiplier counter position by which multi-
plication is taking place receives an advancing
pulse at 12 of each cycle, as indicated in the se-
quence chart in the lower section of Figure 109.
Observe that no rolling pulses can ever enter the
multiplicand counter during the first adding cycle
of a column shift cycle, because the first multi-
plier advancing pulse does not come until 12 of
the first adding cycle, and this is after the adding
portion of the cycle. The first adding cycle is used
for half-entry during the 6th column shift cycle.
The multiplier digit always advances from 9 to
O
in that adding cycle of the set of ten which is
the tens complement of the controlling multiplier
digit. Multiplicand entries start on the succeeding
cycle, so that the number of multiplicand entries
in any column shift cycle equals the value of the
multiplier digit. As shown in Figure 109 at 12 of
the sixth adding cycle, the multiplier position con-
taining a 4 advances from 9 to
O.
Consequently,
during the 7th through 10th adding cycles, the
multiplicand will receive 10 rolling pulses. How-
ever, only 6 of these pulses will reach the product
counter during each adding cycle because of the
6 standing in the multiplicand counter. This part
of the operation is explained later with reference
to the multiplicand read-out.
Observe also from Figure 109 that the multiplier
advancing pulse during the 10th primary cycle is
used only to bring the multiplier reading back to
its original reading. This is necessary when group
multiplying, because the same multiplier is used
for a group of cards.
The circuit for producing the multiplier ad-
vancing pulse at 12 is shown in the A chassis cir-
cuit (Section 24A) and consists of trigger A3 5
and power tube A36. Note that indicator light 7
in socket A13 shows the status of A3 5.
Figure
110 shows the same circuit together with the tim-
ing chart for the operation. The pulse produced
is used to control a switch, therefore, a positive
pulse must be produced at 12 of each primary cycle.
Trigger A35 is initially
OFF
by cancelling, hence,
neirher positive nor negative pulses applied to the
ON
side (A3 52) will have any effect until A3 5 is
turned
ON.
A3 5 is turned
ON
by the first negative
pulse applied to its
OFF
side (A351)
;
positive
pulses have no affect as has been pointed out pre-
viously.
A351 receives a
+
pulse at
O
and a
-
pulse at 8 from A29, the fourth stage of the pri-
mary timer; consequently A3 5 goes
ON
at 8. Ob-
serve from the timing chart that A352 also receives
a
-f 8 pulse.
This will not affect the operation.
When A3 5 goes ON, a positive pulse is produced
at rhe anode of A351 as the potential rises from
about t 4 0 volts to +I40 volts.
This pulse is
transmitted to the grid of power tube A36 but it
has no effect since A36 is normally conducting
The next negative pulse to A3
5 2
from A28 (the
third stage of the primary timer) comes at 12;
consequently A35 goes back to its
OFF
status at
12. At this time the potential at the anode of
A351 drops, and this negative pulse is transmitted
to the grid of A36. A36 momentarily stops con-
ducting, thus permitting the potential at its anode
to rise to +I50 volts and producing a positive
pulse at 12 to pass on to the multiplier entry
switches. A35 repeats this operztion once for
each primary cycle.
The multiplier input switches for controlling
entries to the multiplier counter are located on the
C chassis and consist of 6SK7 type switch tubes;
C3, C6, C9, C12, C15, and C18 for the first
through sixth positions of the multiplier counter
respective1 y.
The read-in triggers and switches shown on the
C chassis are exactly the same as the ones on the
D
chassis and have already been explained. Note
that the multiply control switches utilize the same
load resistors as the read-in switches. This is per-

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