In computing, output padding is the insertion of non-printing characters into the device output stream to allow for a preceding control operation to take effect.
Output padding was necessary on many printing devices, notably
Teletype and other mechanical terminals, after the issuance of a
carriage return. Without the padding, following characters might print in the middle of the output line.
Output padding was also necessary on many
display terminals after cursor positioning, scrolling, and other commands.
Typically the
null character was used; the
delete character
The delete control character (also called DEL or rubout) is the last character in the ASCII repertoire, with the code 127. It is supposed to do nothing and was designed to erase incorrect characters on paper tape. It is denoted as in caret notati ...
was occasionally used. The number of padding characters depended on the particular device, but also sometimes on the horizontal position of the printing
carriage
A carriage is a private four-wheeled vehicle for people and is most commonly horse-drawn. Second-hand private carriages were common public transport, the equivalent of modern cars used as taxis. Carriage suspensions are by leather strapping an ...
.
Notes
Text user interface
Computer terminals
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