On 29 May 2016 at 20:15, [email protected] <[email protected]> wrote: > Tangent: is it true as written that *all* "teletypes speak 5-bit ITA2 code > <https://en.wikipedia.org/wiki/Baudot_code#ITA2>"? > As Ed, Jon, and Chuck said; no not *all* teletypes speak 5-bit code. The "most common" machines in the classic computing community of the Model 33 family (ASR and KSR) speak 7-bit ASCII 1963 with a parity bit (either marking parity, or even parity; usually).
The 5-bit equivalent to the Model 33 is the Model 32, as Chuck mentioned. Similarly, there are other ASCII machines, the Model 35 family, for one is absolutely beautiful; it's based on the mechanisms of the older (and tank-like) Model 28 family. In fact if I recall what was said on the Greenkeys list, the Model 35 parts all have the same names as their corresponding Model 28 parts, except with an '8' in the name. But ask an actual expert. Also, just to be slightly nit-picky, many 5-bit code speaking Teletype machines made in/for the US speak the similar, but not quite the same USTTY code. It only differs in the figure shift, where the bell and apostrophe characters swap places (bell is on J in the standard, S in USTTY), WRU (figure shift of D) is replaced with a normal printing character (dollar sign), and the "national use" characters of F, G, and H are defined as the excalamation mark, ampersand, and number sign. The remaining figure shift characters are completely compatible (and the letter shift doesn't differ at all). Hence why in the ACPs that deal with teletype communications the acceptable characters for use include only those which are held common between the two versions of ITA2 and USTTY. And also why the bell code for Flash precedence messages is <FIGS>JJJJJSSSSS<LTRS> (so that no matter if the message ends up in Europe or the US, the machine's bell will ring). (See: ACP-127(G), paragraph 137.e.) Also, being I'm a process engineering student: The article makes it seem like current loop signalling is a weird dead interface standard; it's not. Current loop isn't that confusing a thing to deal with. We still use it for whenever we need to have electrical signalling that is more noise resistant or goes a longer distance than voltage level signalling. Problem is that current loop converters cost way too damn much. Also, unlike the generic "RS-232C on one end, 20mA current loop on the other" converter boxes that are dumb as a bag of hammers, the board in question has some active electronics for conversion "stuff"; which makes the board infinitely more cool. Cheers, Christian -- Christian M. Gauger-Cosgrove STCKON08DS0 Contact information available upon request.
