Ultimate trivia: how many separate symbol combinations are used in the version of Murray code employed for Telex, and why?
According to the WU Technical Review, there were different variants of the Baudot code used in different applications. For example, certain uses had fractional symbols. Another use had weather symbols. It didn't really matter as long as the keyboard and typebars of the sending and receiving machines were coordinated.
The Wikipedia entry explains some of this.
Sorry, I didn't write my question clearly. I wasn't asking about changing keytops and type pallets, which would IIRC be at the "Presentatin" layer of the OSI Reference model: I don't doubt that it was commonplace, but (again, IIRC) I was asking about the "MAC" layer.
There are 32 combinations of bits available from a 5-unit code such as Baudot/Murray. They weren't all used, though, at least in the CCITT #2 alphabet, and I'd like to know why.
Bill
Would it be that the code point with no holes wasn't used?
I don't know. In a sense, it was: IIRC, it was "used" to punch tape leader at the start of a message, but there were other possibilities which were never employed.
The Murray code has "Figures" and "Letters" codes, which were used to shift the platen up for the "Figures" mode and down for the "Letters" mode. They weren't used for anything else AFAIK, so that leaves (32 -
2) = 30 x 2 + 2 = 62 code points. However, some weren't used, and I've always wondered why.Bill
I'm not sure if this article from the WUTR answers your questions, but it is an interesting look at the code variations and teleprinters used by Western Union in the 1950s:
Cabling-Design.com Forums website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.