Centronics History

Centronics Data Computer Corporation  (sometimes mis-spelled as centronix) was a printer manufacturer spun off from Wang Laboratories in the 1970's and is arguably the company we have to thank for the dot matrix impact printer. They eventually sold the printer business to GENICOM and that was eventually merged with Tally, an old competitor of Centronics to form Tally Genicom^{^}

The Centronics interface, who's name we still use from time to time when refferring to a parallel printer cable or one of its connectors, was developed by Dr. Wang et all to take advantage of an overstock of Amphenol 36-pin ribbon cables originally intended for calculators. It was used on Wang computers and Centronics printers, and so competitors who wanted to replace either had an incentive to follow that standard. HP adopted it for thier printers including the first LaserJets and improved it for bi-directional communications on the LaserJet 4. Eventually, it was officially standardized by the IEEE 1284 standards board and the result is what we have today: The standard parallel port on the back of just about every printer.

Each addition to the original Centronics standard has been made in such a way as to allow the original equipment to continue working. The only major issue is that the original spec called for the busy signal to toggle once each line of printer text, and the current standard calls for it to toggle once for each character, allowing the printer to signal that it is ready for the next.

Questions:

• @spam@amsbradley at KILLspamblueyonder.co.uk asks:

  Do you have info on the Atari ST Centronics port? Apparently, it was almost, but not quite industry standard. This is causing me problems printing from an emulated ST running on a modern PC...

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