View source for Teletype

'''Teletype''' is the commonly-used name for the mechanical [[printing terminal]]s for connection to an [[asynchronous serial line]] produced by the Teletype Corporation.

[[Image:asr33.jpg|200px|right|An ASR33]]

Many different models were produced over the years, but the one most commonly used with computers was the Model 33, which used the [[ASCII]] code (uppercase only), one of the first to do so. 

Although an [[EIA RS-232 serial line interface|EIA]] interface option has reportedly been seen, most used the [[20mA current loop serial line interface|20mA current loop]] interface. 

It operated at 10 characters per second, and used a cylindrical typewheel to print. It was initially produced in the mid-60's, but production continued until 1981; its low cost made it a popular choice. 

The Model 33 came in three different variants:

* ASR (Automatic Send/Receive) - in addition to the keyboards and printer, it included a [[paper tape]] reader/punch on the side
* KSR (Keyboard Send/Receive) - as above, but no paper tape reader/punch
* RO (Receive Only) - only the printer

The ASR-33 (formally the "Model 33 ASR") was widely used on early [[minicomputer]]s, in part because the paper tape option could be used to load [[binary]] program tapes.
 
The later Models 37 (15 cps) and 38 (10 cps) added lower case, a number of special symbols, and a two-colour (red/black) printing ribbon; they too were available in ASR, KSR and RO variants.

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==External links==

* [https://onlineonly.christies.com/s/firsts-history-computing-paul-g-allen-collection/teletype-asr-33-110/230048?ldp_breadcrumb=back Teletype ASR 33] - a Model 33 from [[Paul Allen]]'s collection at the [[Living Computer Museum|LCM]], includes several images
* [https://onlineonly.christies.com/s/firsts-history-computing-paul-g-allen-collection/teletype-asr-35-130/230068?ldp_breadcrumb=back Teletype ASR 35] - a Model 35 from the same collection, also includes several images
* [http://homepage.cs.uiowa.edu/~jones/pdp8/UI-8/ks7470oil.shtml About KS7470 oil and KS7471 grease] - Modern equivalents for Teletype lubricants

[[Category: Printing Terminals]]