12 Apr
2001
12 Apr
'01
2:23 a.m.
The API had RS-232, 20 ma current loop, and parallel, all on the one connector.
I actually had a couple of those. I'm ashamed to admit I once owned and used
eight daisywheel printers in order to generate letter-quality output. I was too
cheap to buy a laser printer, and the "lotsa printers" got the work out. They
made "lotsa noise" too. I wonder how long it will be before I stop finding
spare logic boards, ribbons, and printwheels.
Dick
----- Original Message -----
From: "Don Maslin" <donm(a)cts.com>
To: <classiccmp(a)classiccmp.org>
Sent: Thursday, April 12, 2001 12:02 AM
Subject: Re: 50 pin SCSI to 50 pin centronics
On Wed, 11 Apr 2001, Richard Erlacher wrote:
<snip>
Just to muddy the waters a tad, do not forget that Xerox used a 50-pin
Ribbon connector on some version of the Diablo 630 (IIRC) in what they
called their (A)ll (P)urpose (I)nterface - API - which included
parallel, serial, and I forget what all else.
- don
> Centronics was using that 36-pin connector before Radio Shack ever
contemplated
> getting into the compuer business. It was on the
Printronix P100 we had on
our
> Wang 2200 MVP back in '75. The very first
time I ever saw a real parallel
> printer cable that didn't use the Centronics standard 36-position connector
at
> both ends was on a PC, in 1981. Prior to that,
the "toy" interface used by
the
> Apple II was the only non-homemade one I saw in
use on a commercial system.
> That was understandable in view of the package size constraints, however.
>
> Dick
> ----- Original Message -----
> From: "Tony Duell" <ard(a)p850ug1.demon.co.uk>
> To: <classiccmp(a)classiccmp.org>
> Sent: Wednesday, April 11, 2001 5:51 PM
> Subject: Re: 50 pin SCSI to 50 pin centronics
>
>
> > >
> > > The 50-position type was around for a long time, i.e. I remember them
back
> in
> > > the early '70's and they weren't new then, in use with telecom
gear.
I've
> no
> > > idea whether the 36-position variety was made_for_Centronics, but it's
the
> only
> > > connector that I've ever seen used on a genuine Centronics parallel
> interface,
> >
> > At the printer end, probably (although there were a _few_ pre-PC printers
> > that used a card edge or a header plug for a Centronics-like interface --
> > the Radio Shack Quick Printer 2 was one such IIRC).
> >
> > At the computer end, there were many connectors used. Some companies used
> > the 36 pin Blue Ribbon (I believe that _is_ the correct name). Others
> > used a header plug or a card edge, normally pinned out so that an IDC
> > ribbon cable with no twists could be used to link it to the 36 pin
> > connector at the printer end. Things like the 34 pin card edge on the old
> > TRS-80s, for example.
> >
> > > be it on a Centronics, Printronix, Okidata, (not the toys found attached
to
> a
> > > PC, but the real "line-printers" ) or whatever sort of printer.
The
> interface
> > > used on the PC parallel port does not precisely conform to the
Centronics
> >
> > The PC printer port was designed to link to the 5152 printer which was a
> > badge Epson IIRC. That's why the interface is not _exactly_ Centronics.
> >
> > > standard, and was the first one I saw using a different connector. The
> point is
> > > that while the connector isn't exclusive to that interface, the
interface is
> > > exclusively dedicated to that
connector, to wit, it's still what's used
on
> > > printers, even though everybody knows
it's only going to be attached via
a
> DB25
> > > at the computer end.
> >
> > Round here it might be _anything_ at the computer end :-)
> >
> > > there
> > > > > even existed any notion of a standard for SCSI. The old SCSI-1
uses
a
> > > > > 50-position connector that
looks like the Centronics type. Prior to
> SCSI
> > > fame,
> > > >
> > > > Sometimes. Sometimes (and this is in the standard IIRC), SCSI-1 used
a
> > > > DD50 connector.
> > > >
> > > That's the one widely used by SUN. It's a better connector, but
since
they
> >
> > And others. The Ill-fated PERQ AGW3300 (aka PERQ3a) has a DD50 SCSI
> > connector on it.
> >
> > > didn't make a crimp-onto-ribbon-cable version until very late in the
game,
it
For SCSI, I've neve seen anything bu the crimp-on IDC type. The pinout of
SCSI-1 using that connector was chosen so you could crimp a DD50 onto a
normal SCSI ribbon cable and get the right connections.
Of course this doens't mean the connector didn't come out relatively late
-- I have no idea when the IDC version of the DD50 was first produced.
-tony