On Mon, Dec 14, 2015 at 9:15 PM, Fred Cisin <[email protected]> wrote: > On Tue, 15 Dec 2015, Mike Ross wrote: >> >> I thought Centronics dated back to early 1970s - not always in the >> standard 'modern' form, but in general principles with same signaling >> and strobing of data. > > I got in late. My first encounter with Centronics was TRS80 (1979?) > At that time, Centronics did not yet have a monopoly on parallel > "protocols", although the company had certainly been around for a while.
My first experience was in the mid-1980s. Someone gave me an ancient tank of a Centronics-brand printer - 132 columns and 2 print heads! One head got the left side of the paper, the other head got the right side. Unlike the later "Centronics Interface", this one had an internal edge connector for input - 40 or 44 pins (I used a standard 44-pin protoboard but I can't remember if I had to cut it down or not) I interfaced it to the user port on my Commodore 64 and wrote my own handler to trap device #4 and squirt out the data through the user port. > Once they got the TRS80 market, and then the IBM PC market, any other > designs faded away fast. Yep. About the only exceptions I can think of are the Amiga 1000 (proprietary but similar parallel port pinout on a DB25M) and DEC minicomputers which leaned towards the Dataproducts-type interfaces that required a gate or two (and probably a cable pin swabber) to talk to "modern" Centronics printers - one example was the DC37 on the back of a VAX-11/730... you had to add somewhere between 1-3 inverters to make that talk "Centronics" but once you did, you could just tell the VMS line printer process to squirt chars out the parallel interface and it would "just work". -ethan
