IBM 1401 - Character and Op Codes

Character and Op Codes

The table is in Character Collating Sequence.

Note: If Word mark bit is set, then the C bit will be opposite of shown. Of course, the C bit was determined and checked automatically by the machine - normally it was of no concern to the programmers. The only way the C bit could be entered was by manually using the switches on the Auxiliary Console. A programmer might use these switches to make quick patches while debugging.
This article contains special characters. Without proper rendering support, you may see question marks, boxes, or other symbols.
BCD Character Print-A Print-H Card BCD

w/o M

Operation Definition & Notes
Blank C
. . . 12-3-8 BA8 21 Halt
¤ ¤ ) 12-4-8 CBA84 Clear Word Mark Lozenge
[ 12-5-8 BA84 1
< 12-6-8 BA842 Less Than
12-7-8 CBA8421 Group Mark
& & + 12 CBA
$ $ $ 11-3-8 CB 8 21
* * * 11-4-8 B 84
] 11-5-8 CB 84 1
; 11-6-8 CB 842
Δ 11-7-8 B 8421 Delta (Mode Change)
- - - 11 B
/ / / 0-1 C A 1 Clear Storage
, , , 0-3-8 C A8 21 Set Word Mark
% % ( 0-4-8 A84 Divide Optional special feature.
ˠ 0-5-8 C A84 1 Word Separator
\ 0-6-8 C A842 Left Oblique
0-7-8 A8421 Tape Segment Mark
ƀ N/A

0

A Cannot be read from card without a no-cost RPQ, in which case it is read as 8-2.

Punches as zero. Blank with "even-parity" on tape.

# # = 3-8 8 21 Modify Address Optional (requires more than

4000 characters of memory)

@ @ ' 4-8 C 84 Multiply Optional special feature.
: 5-8 84 1
> 6-8 842 Greater Than
7-8 C 8421 Tape Mark
? & & 12-0 CBA8 2 Zero and Add Plus Zero
A A A 12-1 BA 1 Add
B B B 12-2 BA 2 Branch
C C C 12-3 CBA 21 Compare
D D D 12-4 BA 4 Move Numerical (Bits)
E E E 12-5 CBA 4 1 Move Characters and Edit
F F F 12-6 CBA 42 Control Carriage (Printer)
G G G 12-7 BA 421
H H H 12-8 BA8 Store B-Address Register Optional special feature.
I I I 12-9 CBA8 1
! - - 11-0 B 8 2 Zero and Subtract Minus Zero
J J J 11-1 CB 1
K K K 11-2 CB 2 Select Stacker and other device controls (Card and some others)
L L L 11-3 B 21 Load Characters to Word Mark
M M M 11-4 CB 4 Move Characters to Word Mark
N N N 11-5 B 4 1 No Operation
O O O 11-6 B 42
P P P 11-7 CB 421 Move Characters to

Record or Group Mark

Optional special feature.
Q Q Q 11-8 CB 8 Store A-Address Register Optional special feature.
R R R 11-9 B 8 1
0-2-8 A8 2 Record Mark
S S S 0-2 C A 2 Subtract
T T T 0-3 A 21 Translate (1460 only)
U U U 0-4 C A 4 Control Unit (Tape)
V V V 0-5 A 4 1 Branch if Word Mark

and/or Zone

W W W 0-6 A 42 Branch if Bit Equal Optional special feature.
X X X 0-7 C A 421 Move and Insert Zeros Optional special feature.
Y Y Y 0-8 C A8 Move Zone (Bits)
Z Z Z 0-9 A8 1 Move Characters and

Suppress Zeros

0 0 0 0 C 8 2
1 1 1 1 1 Read a Card
2 2 2 2 2 Write a Line
3 3 3 3 C 21 Write and Read
4 4 4 4 4 Punch a Card
5 5 5 5 C 4 1 Read and Punch
6 6 6 6 C 42 Write and Punch
7 7 7 7 421 Write, Read, and Punch
8 8 8 8 8 Start Read Feed Optional special feature.
9 9 9 9 C 8 1 Start Punch Feed Optional special feature.

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