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Appendix F - 1621 Paper Tape
Paper Tape
and
Paper
Tape Code
Data is punched and read as holes in a 1-inch-wide
chad paper tape (in chad paper tape the holes are
completely punched out), at a density of ten charac-
ters to the inch. An 8-track paper tape code is used.
Seven positions, or tracks, across the width of the
tape are used for coding numeric, alphabetic, and
special characters. One track is used for
EL
(end-of-
line) characters. Figure 70, representing a section of
paper tape, illustrates the eight tracks and all coded
characters.
The lower four tracks of the tape (excluding the
feed holes) are used to record numeric characters in
the
BCD
mode. For example, a hole in track 1 repre-
sents a numeric 2; a combination of 1 and 2 punches
represents a numeric 3; and so on.
The X and 0 tracks are used in combination with
the numeric tracks to record alphabetic and special
characters in a manner similar to zone punches in
IBM
cards. A Read Numerically instruction causes a
single X punch to read into core· storage as a Hag bit
(negative zero).
The check track is used to establish correct parity.
As a check that every character is recorded correctly,
each column of the tape is punched with an odd num-
ber of holes. The
EL
track is not considered in the
parity check.
Tape Specifications
The 1621 Paper Tape Unit is designed to operate with
IBM
paper tape, PIN 304469 (Figure 71). Other paper
tape of equivalent paper stock may be used, but it
must conform to Electronic Industries Association
specifications, RS-227.
The specifications for dimensions of punched tape
can be determined after conditioning the tape to the
following requirements for 24 hours:
75°F
±
3.5
0
50% RH
±
2%
Tape Splicing
Paper tape handling and processing will occasionally
require tape splicing when paper tape needs to be
altered in length, edited, or repaired.
If
possible, a
splice should be made in nondata portions of the
tape. The ability of the paper tape reader to success-
fully and reliably read spliced tape depends upon the
quality of the splice. The following is a procedure for
manually splicing two lengths of paper tape together:
1. Punch tape feed codes into the two ends of
the tape to be spliced together.
2. Cut the tapes at approximately a 45° angle.
3.
Holding the ends of the tape with the tape feed
holes, overlap the tape end in the left hand
over the tape end in the right hand approxi-
mately 1/16 inch.
4. Glue in this position with holes aligned, using
a quick-setting glue such as
IBM
tape muci-
lage, PIN 221030.
Other methods of tape splicing require the use of
special tape splicing equipment.
The use of tape splicing equipment should be con-
sidered if it becomes necessary to repeatedly edit
tape or alter the length of tape. Special splicing equip-
ment and materials will provide efficient, accurate,
and more permanent tape splices. The selection of
appropriate splicing equipment, from the many types
now being offered by various manufacturers depends
TRACKS
EL _ _
~ABCDEFGHIJKLMNOPQRSTUVWXY
Z I 234567890
) • • (
t
-
x _ _ _
0 - - -
CHECK_
8 _ _ _
FEED_
4.,-.---
2 - - -
1 - - -
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~:
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Figure 70.
Paper Tape Codes
86
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