[cctalk] Re: RS232 Spec

Ah, that 1.8GB TIF is just the cover page - scanned at 1200 DPI of mostly white! That's nuts (that it ends up at 1.8GB, isn't TIF using LZH?) But the COCR link is it (not apparent to me what COCR is referring to? but the document is what I recall coming across a while back). I scanned through the 1960s Datamations, and of the editions available (thanks to bitsavers), two notable entries: #1) 1962 March pg 58 "A Criticism of Inactivity" (in relation to "data communication"). H. E. Rennacker basically complains about the lack of data-communication standards across systems. It is insight to see the industry clearly identifies the need and benefits of doing so, while also observing that even by this time (1962) "RS-232" doesn't appear to be a fully recognized/known standard. [ my take is that the early DataSet 103A usage of pins is implicitly what RS-232 "A" would be; the earliest DataSet 103A manual I see is from 1967, even though the concept and similar equipment was probably in use a couple years earlier ] #2) The earliest complete reference to "RS-232" that I found was not until the November 1966 edition (where the entire issue is dedicated to the topic of "communications"). Note that I understand RS-232 mostly relates to electrical characteristics and form factor (with that 25-pin connector coming from Canon in the 1950s?? Then as mentioned above, the Bell DataSet effectively set the standard on which pins ought be used for what for serial communication). I also understand this is just when things were written down, in practice vendors were using all this again several years earlier (sort of like later modem compression protocols, or even later WiFi protocols -- to see if it was worth documenting, someone had to try it in "at-risk-early-adopter" product). Per regular Wikipedia on RS-232, it references " Standards for Computer Aided Manufacturing" which has this to say about RS-232A and B: ************************** 7. Standardization Status: RS-232, May 1960; RS-232-A, October 1963; RS-232-B, October 1965. RS-232-C is expected to be gradually (ten years) replaced by EIA SP-1194A (see writeup immediately below). 8. Implementation Status: Commerically, RS-232-C has enjoyed universal acceptance as the data terminal -to-modem de facto interface. Although MIL STD 188C prescribes 232-C functions, it employs different (lower voltage and lower impedance) electrical characteristics , primarily for security and privacy purposes. ******************************** Looking at the dates, it seems to me RS-232-A (if May 1960) does coincide with the DataSet 101 being more publicly known (c. 1959/1960), and RS-232-B (if Oct 1963) coincide with the DataSet 103A's release. Anyway, just poking around, no specific question here :) Wel, except a related/unrelated question -- why does MIDI use 5mA current loop? And is that why MIDI adopted the joystick port? (IBM original joystick card spec, didn't it involve measuring electrical discharge? so it is effectively a current-loop port? is that somewhat accurate?) -Steve On Sun, Apr 20, 2025 at 12:56 AM Chuck Guzis via cctalk < cctalk(a)classiccmp.org&gt; wrote: