morris@jade.jpl.nasa.gov (Mike Morris) (09/22/89)
(Nickolas Landsberg) writes: > > In the above mentioned article, you mentioned that the speed >was around 60 baud. Well, it was actually something called "75-speed" >which indicated a maximum speed of 75 WPM, transmitted in 5-level >"baudot" encoding. After doing all the mumbo-jumbo af adding start/stop >bits, etc. this translates to an equivalent bits-per-second of 56.83 >or thereabouts. A system I worked on once had to monitor transmissions >from a telco switch which also used this. An interesting sidelight is >that they could transmit the full upper-case character set, the numerics >and a goodly supply of punctuation using just 5 bits. (Actually, they >used a "switch" character to flip-flop between meanings of particular >bit patterns. The "alternate" set would continue to be used until >the "switch" character was seen again.) A bit of nit-picking here: the upshift character was called FIGS (for FIGureS, and the downshift character was called LTRS. All the machines had a feature called USOS for UnShift On Space, and sometimes a message would have to be resent because an inexperienced operator would send a message with a lot of numbers on a machine that would drop back to letters and be received on a machine that wouldn't. Smart operators sending strings of numbers would send a FIGS after any space character just in case. As a side note, the standard speeds were 60, 75 and 100 words a minute, using either a standard length stop pulse or a 1.5 length stop pulse. There are electronic speed converters around, most machines came geared for 60, or 66 (WU's own speed). The type-15 and type-19 machines could be geared for 60, 66, or 75, but had maintenance problems at 75. The later type-35 machines could be geared for 60, 75, or 100 wpm, or have a 3-speed gearbox. 5-level machines are still in use in the amateur radio field, and still passing traffic - the name there is RTTY for Radio TeleTYpe, sometimes called "Ritty". Here in Los Angles, much of the local activity is on 146.70 Mhz, and some of the stations are quite sophisticated, using selective call (imagine a answering machine), and answer-back, etc. Bless the man that designed the first UART chip with 5,6,7 and 8 bits/char! Teletype has discontinued parts availability for the Type-15 and Type 19 (which I have in my station) and for the Type-28 (which I may upgrade to soon- for hauling it away!) - all 5-level). BTW, my type-15 is manufacture-dated 1933, and is still in full working condition - I had to replace the internal wiring as the cotton insulation had hardened and cracked, and become oil-soaked. I saw a picture of a type 20 - it was a 6-level machine used in typesetting - the brief story said it was a 5-level unit with a case bit. The type-26 was a light-duty printing drum machine (like the later 32/33 line) - the ones I worked on were just not designed for 8-hours-a-day use. I was told that there was a type 29 and 30, but sever saw literature or any machines. The Type 32 is the last of the mechanical 5-level machines, (I was told it was a redesign of the 26) and it interestingly came in a 3-row and a 4-row configuration. The famous type 33 is the common 8-level machine that I learned BASIC on, interestingly it's stiff keyboard is blamed for the "tersenes" of UNIX (tm). The type 35 is the standard 8-level heavy duty machine. The 37 was an attempt at a upper/lower case 8-level machine - I've only seen 3 in my life, and one of those was in a scrap heap - supposedly it was a maintenance nightmare. The 40 was an attempt at a do-all-end-all integrated system that never made it - I saw only a few in use, and those were used as dumb terminals. The saving grace was the printer - it was built like a mini-IBM-1403, a train mechanism and was almost indestructible. I saw several in use on minicomputer systems, running day in and out with no downtime. The type 42 is a 5-level version of the 43 8-level dot-matrix machine - the one with the strange paper size (8.5 inches wide, _including_ the perforations!). If anybody wants a 43, let me know - I've access to 70 in excellent condition in a warehouse - make offer!. I know several local amateurs that use 43s as logging printers, and as _quiet_ RTTY stations (with UART-based 8-level-to-5-level converters). 8-level RTTY is legal in the amateur service, but is (naturally) incompatible. Packet is slowly replacing RTTY for message handling, due to it's natural connectivity (it's X.25 based) but there are still a lot of people using the old mechanical marvels. Amateur radio has many facets: voice, television (yes, you can own a TV transmitter!), radioteletype, packet, radio astronomy, satelites, and more. If you're interested, look at rec.ham-radio or rec.ham-radio.packet. Sorry if I got off the subject of FIGS & LTRS, but I happen to like the old machines. I spent 13 months working for a TTY sales & service shop, and still dabble a bit. Mike Morris UUCP: Morris@Jade.JPL.NASA.gov ICBM: 34.12 N, 118.02 W #Include quote.cute.standard PSTN: 818-447-7052 #Include disclaimer.standard cat flames.all > /dev/null
kaufman@neon.stanford.edu (Marc T. Kaufman) (09/25/89)
In article <telecom-v09i0398m02@vector.dallas.tx.us> Mike Morris <morris@jade.jpl.nasa.gov> writes: >As a side note, the standard speeds were 60, 75 and 100 words a minute, >using either a standard length stop pulse or a 1.5 length stop pulse. The mechanical stop pulse was 1.42 bits long. This has to do with the time required to mechanically unclutch and reclutch the motor to the decode wheel. > The Type 32 is the last of the mechanical 5-level machines, >(I was told it was a redesign of the 26) and it interestingly came in a 3-row >and a 4-row configuration. Was there a 4-row 32, or was it really the 33? I had all the catalogs, and never saw a 4-row 5-level machine. > The famous type 33 is the common 8-level >machine that I learned BASIC on, interestingly it's stiff keyboard is >blamed for the "tersenes" of UNIX (tm). The type 35 is the standard >8-level heavy duty machine. The 37 was an attempt at a upper/lower case >8-level machine - I've only seen 3 in my life, and one of those was in >a scrap heap - supposedly it was a maintenance nightmare. The 37 had a typebox like the 35, but twice as large (for the lower case characters). It ran at 150 bps. 15 characters per second was just slightly too fast for the mechanical parts to keep up. It also had a two color ribbon, with the color switch available via the "stunt box" (a special relay bank tripped by certain character sequences). >The 40 was >an attempt at a do-all-end-all integrated system that never made it - I >saw only a few in use, and those were used as dumb terminals. The >saving grace was the printer - it was built like a mini-IBM-1403, a >train mechanism and was almost indestructible. I saw several in use >on minicomputer systems, running day in and out with no downtime. There was one model of the type 40 printer that would allow you to rip off the top form (the one just printed) without wasting the form below. It was used extensively by travel agencies and ticket sales outlets... anywhere serialized form stock was required. Marc Kaufman (kaufman@Neon.stanford.edu)
msc@ihc.att.com (Michael S Cross) (10/18/89)
[Moderator's Note: Michael Morris passed along this letter received from
Mr. Cross, in response to an earlier article in the Digest. PT]
I just finished reading your description of the TTY machines and just
wanted to say hello. The building I am in now is one of the last
TELETYPE buildings left standing. Just after divestiture we became
AT&T TELETYPE then just AT&T, we are now AT&T Bell Laboratories (for
about 1 1/2 years). We don't make printers anymore :-( Now our
standard products are the 6500 Multifunction Communications Controller
(IBM 3270 Market) and the 630 MTG.
We are moving to Naperville IL next Feb. providing the building is
complete. The land has been sold to developers who are erecting a
shopping center as we "speak". About the only things left to remind
us of TELETYPE are the Water Tower and our computer names. My main
machine, ttrdc, was shutdown last week and we have aquired a
mail-server named 'ihc' for Indian Hill Court, the name of our new
building. (this is a NetNews-server, cbnewsc) I feel sad that we are
loosing our "heritage", but data communications just ain't what they
used to be. Gotta go now, take care!
Michael S. Cross (msc@ihc.att.com) (312)-982-2018
AT&T Bell Laboratories, 5555 Touhy Ave., Skokie, IL 60077
______________________To Live is to risk Dying____________________________