20 Apr
2025
20 Apr
'25
7:30 a.m.
On Apr 19, 2025, at 11:41 PM, Steve Lewis via cctalk <cctalk(a)classiccmp.org>
wrote:
Hey gang, a few months ago I had found the 1968/1969 document spec of
RS-232. But now, I'm unable to find it again !
At Internet Archive, there is one link/reference to it, but it appears to
just be the cover page (which does have the date of August 1969).
I see the EIA RS-232-C spec dated from 1991 (but I think that date is just
marking when EIA took over stewardship of the standard, but the spec should
reflect/match the original 1969 one).
Could this be what you’re searching for? The site just tells you what libraries have
copies, but perhaps having the exact title/date will help you find an online copy
somewhere if you don’t have access to one of the libraries with a copy.
https://search.worldcat.org/title/3642114
Title: Interface between data terminal equipment and data communication equipment
employing serial binary data interchange
Author: Electronics Industry Association
Print Book, English, 1969
Publisher: EIA, Washington, 1969
Pages: 29
Series: EIA Standard RS-232-C
OCLC Number / Unique Identifier: 3642114
In the manual for the DataSet 103C (from a few years earlier than 1969), it
outlines signal lines all labeled like RS-232. But I wouldn't call it an
RS-232 spec.
Like most standards, it takes a number of years for a community/critical
mass of products to understand it and adopt it correctly. Even ASCII
wasn't globally recognized and adopted until maybe 15 years after it was
introduced? So I was trying to track down the "earliest mention" of
RS-232, to pinpoint it really being from 1962.
Technically it appears the EIA "guards" that spec, and makes it expensive
to officially download it. Maybe they took an initiative to try to scrub
earlier editions from the public web, maybe that's why it's harder to find
now? But I was pretty sure I found a scanned copy of it at some point (the
Aug 1969 one).
If anyone happens to have a printer version (of a 1969 or earlier RS-232
spec) - it would at least be nice to know that exists somewhere. I'm
pretty sure that "original spec" called out +/- 3 to 25V, later ones maybe
used 20V or 15V.
-Steve