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Path: euryale.cc.adfa.oz.au!newshost.carno.net.au!harbinger.cc.monash.edu.au!news.rmit.EDU.AU!news.unimelb.EDU.AU!munnari.OZ.AU!news.Hawaii.Edu!news.uoregon.edu!arclight.uoregon.edu!usenet.eel.ufl.edu!warwick!lyra.csx.cam.ac.uk!ard12 From: ard12@eng.cam.ac.uk (A.R. Duell) Newsgroups: comp.unix.misc,comp.unix.bsd.misc,alt.folklore.computers Subject: Re: On the Naming of UNIX Things Date: 18 Nov 1996 19:35:35 GMT Organization: University of Cambridge, England Lines: 71 Message-ID: <56qdq7$k11@lyra.csx.cam.ac.uk> References: <55vhpf$q3o@mail1.wg.waii.com> <56ivb8$kbc@uwm.edu> <x7afsiyfqx.fsf@dumbcat.codewright.com> <56q3m1$8db@innocence.interface-business.de> <56q6nv$ch7@nntp.ucs.ubc.ca> NNTP-Posting-Host: club.eng.cam.ac.uk Xref: euryale.cc.adfa.oz.au comp.unix.misc:26517 comp.unix.bsd.misc:1550 alt.folklore.computers:124843 shoppa@alph02.triumf.ca (Tim Shoppa) writes: >>I thought 45.45 was only used in HAM radio (and might still be in use >>there)? And, of course the reason 45.45bps was used in amateur radio was that radio amateurs used surplus teletype machines - very few amateurs could make something like a (mechanical) teleprinter at home ;-) >No, 45.45 was a common speed for 5-level teletypes, at least in >the U.S. A very worthwhile thread to start up would be a discussion >of European teleprinter equipment - I've seen a little of it, and there OK... I'll describe a few Creed machines (built in the UK) that I have, and let others jump in with corrections and additions The Creed 7E was one of the very popular Creed 7 machines (Popular, that is, amongst radio amateurs). The transmitting mechanism is fairly conventional - pressing a key sets up 5 encoder rails that are sampled one at a time and set the transmit contact switch. The receiver is somewhat more unusual, in that the printhead is fixed, and the platten/paper roll moves past it. Incoming serial data is applied to a (polarised) electromagnet, and, via a mechanical equivalalent of a UART, sets up the state of 5 levers. This bit is similar in concept (although _not_ in detail) to, say, a Teletype 32. These 5 levers then set the rotational state of 5 notched disks arround the shaft carying the printhead. A 6th disk arround this shaft handles the figs/letts state. Then, 64 bellcrank levers mounted arround the circumference of these disks are released. One drops into a groove formed where all the notches line up, and stops the rotating printhead (which is similar to a daisywheel, although made up of separate metal type slugs). A little printhammer then presses the appropriate slug onto the paper, printing the character. Some of the bellcranks have no corresponding slug, but instead have external levers that trip things like the carriage return or linefeed mechanism when they drop into place. The Creed 6S2 is a paper tape reader for 5-level tape. Somewhat unusualy, the 5 holes are _not_ all read at the same time - the 5 peckers read the holes one at a time and directly set the transmit contact. This gives a serial output, of course. Both these Creed machines use series-wound motors with mechanical governors to set the speed. Adjusting these is a pain as (a) the governor spins round with the motor and (b) it's connected to the mains (as, incidentally is the adjusting screw). The governor casing is painted with black and white stripes, allowing a stroboscope to be used to check the speed. A later Creed machine is the 444, which was used on Telex lines until at least the mid 1980's. It's still fully mechanical, but it's a lot more like a Teletype (15 or 28???) - the printhead is now a type basket which slides along 6 rails carrying the 5 bits of the current character and the figs/letts state. It's a very modular machine - it splits up into carriage, function box (special function decoder), encoder, tape punch, tape reader, motor, keyboard, decoder, transfer link, etc very easily. A good reference on these machines is an RSGB (Radio Society of Great Britain) publication called 'The Teleprinter Handbook'. I'm not sure about recent editions, but the older ones had pictures and adjustment instructions (and some circuits/mechanical diagrams) for a lot of teleprinter equipment. >appears to be quite a bit more variety than in the U.S., where >the Teletype Corp of Skokie Illinois had a near monopoly on the market. >Tim. (shoppa@triumf.ca) -- -tony ard12@eng.cam.ac.uk The gates in my computer are AND,OR and NOT, not Bill