much later seven-bit ASCII code, there was a six-bit code known as the Teletypesetter code (TTS) used by news wire services. It was first demonstrated in 1928 and began to see widespread use in the 1950s. Through the use of "shift in" and "shift out" codes, this six-bit code could represent a full set of upper and lower case characters, digits, symbols commonly used in newspapers, and typesetting instructions such as "flush left" or "center", and even "auxiliary font", to switch to italics or bold type, and back to roman ("upper rail"). The TTS produces aligned text, taking into consideration character widths and column width, or line length. A Model 20 Teletype machine with a paper tape punch ("reperforator") was installed at subscriber newspaper sites. Originally these machines would simply punch paper tapes and these tapes could be read by a tape reader attached to a "Teletypesetter operating unit" installed on a Linotype machine. The "operating unit" was essentially a tape reader which actuated a mechanical box, which in turn operated the Linotype's keyboard and other controls, in response to the codes read from the tape, thus creating type for printing in newspapers and magazines. This allowed higher production rates for the Linotype, and was used both locally, where the tape was first punched and then fed to the machine, as well as remotely, using tape transmitters and receivers. Remote use played an essential role for distributing identical content, such as syndicated columns, news agency news, classified advertising, and more, to different publications across wide geographical areas. In later years the incoming 6-bit current loop signal carrying the TTS code was connected to a minicomputer or mainframe for storage, editing, and eventual feed to a phototypesetting machine. Teleprinters in computing Computers used teleprinters for input and output from the early days of computing. Punched card readers and fast printers replaced teleprinters for most purposes, but teleprinters continued to be used as interactive time-sharing terminals until video displays became widely available in the late 1970s. Users typed commands after a prompt character was printed. Printing was unidirectional; if the user wanted to delete what had been typed, further characters were printed to indicate that previous text had been cancelled. When video displays first became available the user interface was initially exactly the same as for an electromechanical printer; expensive and scarce video terminals could be used interchangeably with teleprinters. This was