'This computer [..] is the largest of its type in the world.
It contains five million three hundred thousand cryotrons and is
capable of dealing simultaneously with over one hundred thousand
variables. [..]. The requirements are fed in on tape which is
perforated by the action of this keyboard. [..] The computer can,
in less than an hour, present our scientists with a design for a
brain which will give all the necessary positronic paths to make a
--- Isaac Asimov, The Rest of the Robots, 1969.
From the early days
up till well into the 70's, paper tape was heavily used in the
computer industry as a cheap and reliable means of data storage.
Besides, it was used in telecommunications (telex), and in the
printing industry as the input medium for hot-metal typesetting
machines. Up till the turn of the century it has been in use for numerical control of milling
and drilling machines. For heavy duty applications, paper was often
replaced by synthetic materials like mylar.
In computer applications, tapes were usually 1 inch wide with 8
information hole positions and one sprocket feed hole in each row,
see the top illustration . Occasionally, the narrower 7, 6 or 5
'channel' varieties were used. The dimensions were well
standardized; hence all varieties could be read on an single tape
reader with a minimum of adjustment. One meter of 8-channel tape
can contain about 400 bytes of data.
Paper tape punches have been built with operating speeds from 10 -
300 rows per second. Tape readers worked either mechanically (with
sense pins) or electro-optically. Using the latter technique, very
expensive readers could handle up to 2000  rows per second while
being able to stop on one row. For such fast readers, special
equipment (servo-controlled reels) was needed for feeding the tape
to and from the reader.
A simple solution used with medium-speed
readers (300 rows/s) was to use fan-fold tape, which re-folds
automatically if it is catched from the reader in an appropriately
Special equipment existed for comparing tapes: for critical
applications, data entry was done by two typists at the same time.
By comparing the resulting tapes typing errors could be detected.
Paper tapes could be corrected, edited or repaired easily by
manually adding missing holes, or by cut-and-paste operations,
using some very simple mechanical tools.
Computer paper tapes mostly used parity check for detecting
punch or read errors; the tape fragment shown here uses odd-parity
coding. The diagram  shows the ASCII 8-channel paper tape code
used by the popular Teletype ASR33
electro-mechanical computer terminal. Similar machines like the Friden Flexowriter
used an entirely different
System software for the early PDP8 and PDP11 machines in our
collection was distributed on papertape; we have an almost complete
The Computer Museum has facilities for reading and interpreting
any type of coded paper tape. Tape punchers and a supply of tape
are available as well.
- Handbook of Automation, Computation and Control, Wiley
- Teletype Technical Manual, Teletype Corporation 1964
- J.M. Visscher: Een snelle ponsbandlezer. Philips Technisch
Tijdschrift 28 (1967) pp161-172 (In Dutch)