ASR33
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Introduced about 1963, Teletype Corporation's ASR33 was a very popular model of teleprinter. Designed for light-duty office use, it was much flimsier (and cheaper) than its heavy duty cousin, the Model 35ASR.
The printing mechanism was an array of levers, cranks, and a type wheel on a movable carriage. These mechanical parts printed up to 10 characters per second. Printing was limited to the upper case ASCII character set.
The ASR 33 had a built in paper tape reader and tape punch (8 hole ASCII including one parity bit). It could print and read or punch tape at the speed of 10 characters per second. The ASR33 tape reader was purely mechanical; 8 spring loaded fingers would be thrust into the tape (one character at a time) and an assortment of rods and levers would sense how high the finger rose, which told it if there was a hole in the tape at that position.
The ASR32 was a similar device, but used five hole Baudot code. The otherwise identical KSR33 and KSR32 models lacked the paper tape reader and punch. "KSR" stood for "keyboard send and receive" while "ASR" stood for "automatic send and receive."
More expensive Teletype systems used photo readers that used light sensors to detect the presence or absence of punched holes in the tape. These could work at much higher speeds (hundreds of characters per second). More sophisticated punches were also available that could run at somewhat higher speeds; Teletype's BRPE punch could run at 60 characters per second.
In the photograph. the two holes appearing on the right side of the teletype are for an optional acoustic coupler to an internal modem. The paper tape reader is on the left and some paper tape can be seen hanging down below the reader.
Basic CRT-based computer terminals which could only print lines and scroll them are often called glass teletypes. Teletypes were gradually replaced in new installations by dot-matrix printers and CRT based terminals in the mid to late 1970s.
