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Circuit Description; Write Numerically (Code 38-Wn); Objective; Functions - IBM 1620 Manual Of Instruction

Data processing system, model 2; plotter control unit; plotter feature
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WRITE NUMERICALLY (CODE 38-WN)
The 1626 block diagram for Op Codes 35, 38, and
39 and the function charts contained in the 1620 Sys-
tem Diagrams are used to supplement the following
circuit description.
Objective
• Transmit numerical information, including
flag bits, from the memory location desig-
nated by the P-address (OR-2) and succes-
sively higher memory locations to the output
device specified by the Q8 and Q9 digits of
the instruction.
Functions
During I-cycles, the Q8 and Q9 digits of the instruction
are placed in the Digit/Branch register and decoded
to specify the output device. The plotter is specified
by 02.
The digits of output data are transmitted serially
from the memory location designated by the P -address
(OR-2) and successively higher memory locations to
the selected output device.
Flag bits in memory with
digits of output data are recorded with the digits by
the output device.
Alphabetic characters, special characters, and
numerical characters that have been stored in mem-
ory as two adj acent digits because the computer was
in alphameric mode, are recorded by the output de-
vice as two numerical digits.
The write operation leaves output data unchanged
in memory.
Transmission of a numerical character of output
data to the plotter requires plotter motion corres-
ponding to the paper tape code for the specific digit.
The Write Check latch is turned on when the
following condition exists:
A character with incorrect parity is presented
to the output device by the output translator.
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.
227-5811-0 (11-63)
SECTION 2
CmCUIT DESCRIPTION
With the plotter as the output device, the write
operation is terminated by one of the following:
1.
Sensing a record mark from memory.
Termination of the write operation directs
the computer to enter the I-cycles 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 then required
to restart the computer .
Circuit Objectives
Write Latch (11. 83. 03.1-10. 01. 51.1).
1.
Turned on by 1-6.
2.
Turned off by I/O Exit (Record Mark
detected) .
3.
Block ''Run Clock" control.
4.
Turn on (T17D2) I/o Memory Control
latch during 1-6 time.
I/o Memory Control A (11. 83. 08.1-10. 01. 53.1).
1.
Turned on by the following:
a.
Write Latch (T1702) during 1-6 time
to set first output character into
MBR.
b.
Response Gate latch for second and
subsequent output characters.
2.
Turned off during the cycle following its
turn on.
3.
Turn on Run Clock latch for one machine
cycle.
4.
Read OR-2.
5.
Write OR-2 incremented 1.
6.
Turn on Character Gate latch.
7.
Gate Output Translator to allow the select
channel digit to punch on the paper tape
punch.
I/O Memory Control Latch B (11. 83. 08.1-10. 05.53.1).
1.
Turned on by I/O Memory Control Latch A
(T11D4) .
2.
Turned off during following cycle (T2D3).
3.
Turn on Write Check latch
if
an even parity
character is detected.
4.
Develops a service response to turn on the
Go latch when the output character is
available in MBR.
2.1

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