"DoN. Nichols" wrote:

On 2014-05-19, Michael A. Terrell wrote:

"DoN. Nichols" wrote:

[ ... ]

Just like what happened with the Amphenol miniature blue ribbon
connectors. Centronics chose the 36-pin version of that as the parallel
printer port. Now, anything which uses one of the series of connectors
gets called "Centronics connector", including the most common (the 50-pin
SCSI interface -- which also used the DD-50 and a miniature quick-lock
connector which I first saw on Sun workstations and drive boxes).
Another (less common) one is the IEEE-488 connector (also originally
called HP-IB by Hewlett Packard, and later when it was made public
domain, GP-IB). That one uses a 24-pin version of the connector, and
usually a weird one on the cable end which has both a male and a female
on back so you can stack them, since you can chain a number of test
instruments on one bus.


I have a half dozen pieces of test equipment with the IEEE-488
interface. There are web pages with USB to IEEE-488 interfaces you can
build.

Hmm ... Can they be talked to with something other than Windows?
I've got an HP card in a machine running Ubuntu linux with an open
source driver for that which happily talks to my HP digital 'scope and
my HP DMM.


Yes. In fact, they were originally controlled by HP's lab style
computers. All you need is a computer with a working HPIB/GPIB/IEEE-488
interface card and the commands for that instrument. The user manual
usually lists the commands for each instrument.


[ ... ]

The interesting thing about the DB-25 and the RS-232 serial port
is that the standards were very careful about the voltages which the
pins would accept and output, and lots of other things, but it did not
bother to specify the actual connector to use. It *could* have been any
of a number of other connectors, as long as it had enough pins. I think
that the use of the DB-25 for that was started by Ma Bell in their
modems -- and everyone else followed suit. :-)


It was a good choice. A reliable connector from Canon, not something
custom from an unknown source.

Indeed. But interesting that the *standards* did not specify a
connector at all. :-)


Yes, but most companies picked a common connector so they could talk
to other equipment without stocking hundreds of different cables. A few
oddballs used very expensive and hard to find connectors. Some used
another cheaper connector to save a few cents, like the Heathkit H-14
printer that used a straight line molded nylon connector like those used
on switching power supplies.

--
Anyone wanting to run for any political office in the US should have to
have a DD214, and a honorable discharge.

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