On Apr 19, 2025, at 11:41 PM, Steve Lewis via cctalk <[email protected]> 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
