IBM 80 User Manual

SPECIAL DEVICES
These relays, with several necessary additional resis-
tors, are mounted inside the standard relay cabinet. All
Type
75 and 80 machines have a circuit cutout relay
to open the machine circuit when the MCS brush is be-
ing handled by the operator. The location of these items
inside the cabinet
is schematically shown on the wiring
diagram for each machine (Refer to the first paragraph
in the
Circuit Description section for these wiring dia-
gram numbers.)
CIRCUIT DESCRIPTION
THE CIRCUITS described herein for multiple· column
selection and zero-elimination pertain
to a Type 82
machine equipped with a multiple column selection
de-
vice. Figure 49 is a reproduction of the multiple column
selection wiring diagram
270096-A. All circuit de-
scription pertaining to multiple column selection and
zero-elimination will refer
to this figure. (The wiring
diagram for a Type
80 machine with MCS is 181914-D;
for a Type
75 machine it is 181916-E.)
Normal Sorting and Common Digit Selection
When the machine is set up for normal sorting or
for selection of a common digit through the
use of the
SC hub, the sorting circuit operates in a similar man-
ner to those circuits described in the Type 82 circuit
description section of this manual.
MULTIPLE COLUMN SELECTION
Static Circuit Conditions
A type 2D21 thyratron tube (MCS control) is con-
nected across the DC machine circuit with a 2000 ohm
resistor in series with its anode. Negative bias for this
tube
is obtained from the standard bias oscillator and
rectifier and
is applied across a voltage divider con-
sisting of a .5 megohm and 1 megohm resistor in series.
A schematic diagram of this wiring
is shown in Figure
'50. The voltage across the 1 megohm resistor is applied
between the control grid and the cathode of the tube
through another
.5 megohm resistor, making the grid
approximately
25 volts negative with respect to the
cathode. This negative grid
bias prevents the tube from
firing when anode voltage
is applied through com-
mutator 2 at the beginning of each card cycle.
The control grid circuit of the tube
is also connected
to the common brush on the A segment of the
MCS
selecting commutator through the number 2 zero-
eliminate switch in the off position.
Sensing a Selected Value (Figure 49)
When a multiple column brush senses a value in the
card which corresponds
to the value of the selector hub
to which the brush is wired, a positive voltage is ap-
plied to the grid of the 2D21 MCS control tube as
follows: from the positive DC terminal 13, through the
CCR-B point, contact roll cover switch
1, card lever
contacts, commutator
2, zero-eliminate switch l-L OFF,
contact roll common brush, multiple column brush,
brush selection switch set to
SELECT, transfer contact,
zone or lower punching hub, control panel wire, selector
hub to which the brush
is wired, selector brush on the
A segment of the selecting commutator, A segment
common brush, zero-eliminate switch
2-L OFF, pin 7
on octal plug
B, two 500K ohm resistors in series, to
the grid of the
MCS control tube. This positive voltage
cancels the negative grid
bias, causing the 2D21 to
fire and remain in conduction until its anode circuit is
broken after 12 time in the cycle when commutator 2
opens.
When commutator 3 makes at
12+
6
3
4
of each cycle,
a positive voltage
is applied to the starting anode of
the OA4G trigger tube through the following circuit:
from the positive
DC terminal 13, through the CCR-B
point, contact roll cover switch 1, card lever contacts,
commutator
2, zero-eliminate switch 1-L OFF, pin 4
on octal plug
B, 2000 ohm resistor, to pin 6 on the
MCS 2D21 tube, through the 47,000 ohm resistor, pin
6 on octal plug
B, commutator 3, multiple column
selection switch
I-RoN, to the outer brush of the sort-
ing selector commutator, through pin 5 on octal plug
A, the 47,000 ohm resistor, to the starting anode of the
OA4G. If the MCS 2D21 has not been fired prior to
the time that commutator 3 makes, the full positive
DC voltage is app'lied to the starting anode of the OA4G,
thus causing the tube to fire and sort that card into the
12 pocket. If the 2D21 tube has been fired prior to
the time that commutator 3 makes, the positive voltage
applied
to the starting anode of the OA4G is not suf-
ficient to fire the tube, thus causing that card to reject.
Current flowing through the
2000 ohm resistance, be-
cause of the firing of the MCS 2D21, causes a voltage
drop through this resistance, thus reducing the
magni-
tude of the positive voltage available to the starting
anode of the
OA4G when commutator 3 makes.
Sensing an Unselected Value
When a multiple column brush senses a value in
the card which does not correspond
to the value of the

IBM 80 Specifications

General

Brand	IBM
Model	80
Category	Office Equipment
Language	English