I do indeed have the printer. Found it on the weekend. No sign of the interface card or cable yet though.
David Collins (Sent from out of office) > On 14 Jul 2017, at 6:02 pm, CuriousMarc via cctalk <cctalk@classiccmp.org> > wrote: > > Ah, thanks, I learned something. The HP 2767 is a weird beast - line drum > printer but only 80 columns, from what I glean from hpmuseum.net. David > (Collins), do you have the printer? > Marc > > -----Original Message----- > From: J. David Bryan [mailto:jdbr...@acm.org] > Sent: Tuesday, July 11, 2017 11:12 AM > To: CuriousMarc > Cc: Classic Computing List > Subject: Re: HP 12653A line printer interface > > Marc, > > >> On Monday, July 10, 2017 at 22:24, CuriousMarc wrote: >> >> I thought I did, but what I have is the HP 12845B Line Printer >> interface card, for which I could find the documentation. > > Thanks for checking. Yes, that does seem to be the more common card. As > far as I know, the 12653A was used only for the HP 2767 (a rebranded Data > Products 2310), whereas the 12845B was used for a number of other HP > printers. > > >> Reading some more, it is meant for the 2607/261x series of printers, >> which apparently use a narrower 7 bit interface (the 12566 is a 16 bit >> interface card). > > Which is all a bit odd, as the 2767 also uses 7 bits for data. Unlike the > other printers that use differential interfaces, the 2767 uses single-ended > TTL-level (more or less) drivers and receivers, which may explain the use of > the microcircuit-based interface. > > The 2767 signal drivers are adjustable for a 3- to 8-volt output level, so > perhaps the 12635A "modification" was to clip the inputs to avoid damaging > the standard microcircuit receivers (7400 TTL with an absolute maximum input > spec of 5.5 V). In the absence of a manual, I was hoping that a photograph > would reveal the modification. > > >> But maybe you can inspire yourself from it. > > The existing 2767/12653 simulation was reverse-engineered from the > diagnostic and OS drivers. Although it works, I was hoping for something > more authoritative so that the code could serve as a reference for the > now-extinct hardware. > > -- Dave > >
