On Tue, 4 Jan 2005, Rob Brown wrote:

> On Mon, 3 Jan 2005, Carl Lowenstein wrote:
>
>> The 9-pin D connector (DE9) used by DEC for serial connections of 11/23
>> vintage predates the use of the same connector in the IBM PC and its
>> compatible world. The pinouts are not the same. You can look it up
>> somewhere on the Web.

>
> The VMS FAQ is a good place.


And to be honest. DEC's pin layout on a DE9 makes a lot more sense than
IBMs. After all, RS232 is actually only defined for a DB25, but if you
were to adapt it to a DE9, I'd say it's much more sensible to keep the
signals at the same pin numbers when possible. The only signal that
actually needs to be moved is 20. (DTR).

But IBM in all it's wisdom decided to change 2&3, and move ground to 5.
Hooray! At that time, IBM wasn't exactly interested in standards. Heck,
before the PC they didn't even care about ASCII, and the PC only
relucantly bowed for that one.

Johnny

Johnny Billquist || "I'm on a bus
|| on a psychedelic trip
email: bqt@update.uu.se || Reading murder books
pdp is alive! || tryin' to stay hip" - B. Idol
----------
To unsubscribe (or subscribe) from (to) this list, send a message to
info-pdp11-request@village.org, with the first line of the message
body being "unsubscribe" or "subscribe", respectively (without the quotes).