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IBM 1620 Manual Of Instruction page 11

Data processing system, model 2; plotter control unit; plotter feature
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cessively higher pairs of memory locations. Each
2-digit memory character is decoded into the proper
numerical, alphabetic, or special character by the
output translator and presented to the plotter.
The P-address of the instruction must designate
the odd -numbered memory location at which the
numerical digit of the first character to be transmitted
is stored. The zone digit of the first character is
located at the next lower memory address (P minus
1) which is an even address. Increment plus 2 is
used to provide memory addresses for successive
character s.
If
an even-numbered memory location is erron-
eously designated by the P-address, data presented
to the plotter is incorrect and parity errors may
occur.
Output data may consist of a random mixture of
numerical and alphabetic characters which exist in
memory as two-digit characters.
If
an attempt is
made to write a record containing single-digit num-
erical characters by means of this instruction,
invalid combinations of disassociated numerical
digits are the result and parity errors may occur.
Flag bits existing in memory locations from
which an output record is written are not transmitted
to the plotter. The write operation leaves output
data unchanged in memory.
227-5811-0 (11-63)
Transmission of a character of output data to
the plotter requires plotter motion corresponding to
the paper tape code for the specific character. A
space is ignored by the plotter.
The Write Check latch is turned on when the
following condition exists:
A character with incorrect parity is pre-
sented to the plotter by the output trans-
lator.
If
the Write Check latch is turned on with the
plotter as the output device, the plotter is stopped
after the corresponding plotter motion is complete.
With the plotter as the output device, the write
operation is terminated by one of the following:
1.
Sensing a record mark at an odd memory
address. Termination of the write opera-
tion directs the computer to enter the
I-cycle for the next instruction in sequence.
2.
Pressing the Release key on the console.
The write operation is terminated immedi-
ately and the computer stops. Pressing the
Start key on the console is required to
restart the computer.
Circuit Objectives
See Write Numerically (Code 38).
2.3

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