On 1/6/06 9:34 PM, in article 43BF5267.24D39FBB@earthlink.net, "Michael A. Terrell" <mike.terrell@earthlink.net> wrote:> Richard Crowley wrote: >> >> "Jim Thompson" wrote ... >>> "techie_alison" wrote: >>>> "Grant Edwards" wrote ... >>>>> Charles Jean wrote: >>>>> >>>>> Who's Mark? >>>>> >>> [snip] >>> >>> Space's brother ?:-) >> >> ROTFL! :-)) >> >> (But likely lost on the younger crowd.) > > > Yeah, they don't know what they missed by never working on the old AP > & UPI newswire KSR33 teletypes on a leased loop.Or the models 14, 15 and 19 that were even before your time. They seemed hi-tech at the time. My first one at home was a 14 with the range crank on top, front. It came from a Telco Toll office.
RS232 Voltage Levels
Started by ●January 5, 2006
Reply by ●January 7, 20062006-01-07
Reply by ●January 7, 20062006-01-07
On Sat, 07 Jan 2006 07:35:18 -0800, Don Bowey <dbowey@comcast.net> Gave us:>On 1/6/06 9:34 PM, in article 43BF5267.24D39FBB@earthlink.net, "Michael A. >Terrell" <mike.terrell@earthlink.net> wrote: > >> Richard Crowley wrote: >>> >>> "Jim Thompson" wrote ... >>>> "techie_alison" wrote: >>>>> "Grant Edwards" wrote ... >>>>>> Charles Jean wrote: >>>>>> >>>>>> Who's Mark? >>>>>> >>>> [snip] >>>> >>>> Space's brother ?:-) >>> >>> ROTFL! :-)) >>> >>> (But likely lost on the younger crowd.) >> >> >> Yeah, they don't know what they missed by never working on the old AP >> & UPI newswire KSR33 teletypes on a leased loop. > >Or the models 14, 15 and 19 that were even before your time. They seemed >hi-tech at the time. My first one at home was a 14 with the range crank on >top, front. It came from a Telco Toll office.Well... take a bow.
Reply by ●January 7, 20062006-01-07
In article <43BF5267.24D39FBB@earthlink.net>, Michael A. Terrell <mike.terrell@earthlink.net> wrote:> > Yeah, they don't know what they missed by never working on the old AP >& UPI newswire KSR33 teletypes on a leased loop.33's were uppercase ASCII. I think the wire services used 5 bit machines. The ones with the type box were 28s. I think the 5 bit code corncob machine was the 32. Mark Zenier mzenier@eskimo.com Googleproofaddress(account:mzenier provider:eskimo domain:com)
Reply by ●January 7, 20062006-01-07
Don Bowey wrote:> > On 1/6/06 9:34 PM, in article 43BF5267.24D39FBB@earthlink.net, "Michael A. > Terrell" <mike.terrell@earthlink.net> wrote: > > > Yeah, they don't know what they missed by never working on the old AP > > & UPI newswire KSR33 teletypes on a leased loop. > > Or the models 14, 15 and 19 that were even before your time. They seemed > hi-tech at the time. My first one at home was a 14 with the range crank on > top, front. It came from a Telco Toll office.I had a model 15 of my own, (Found at a Dayton hamfest) but I used the KSR33 a lot more. We had two of them at the military radio & TV station I worked at in '73 & '74. They replaced our very worn out Kleinschmidts. :-) Later on I had a Metrodata computer with two 20 mA boards for AP & UPI news wires at a United Video Cablevision CATV headend in Cincinatti, Ohio. I was troubleshooting one of the six channel Metrodata graphics computers when I found a couple undocumented commands. One that let me interrupt the 20 mA loop. The other let me type and send messages on a "Read only" system. It wasn't long after that that the hardwire 20 mA loops were replaced with receive only sat equipment. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Reply by ●January 8, 20062006-01-08
Mark Zenier wrote:> In article <43BF5267.24D39FBB@earthlink.net>, > Michael A. Terrell <mike.terrell@earthlink.net> wrote: >> Yeah, they don't know what they missed by never working on the old AP >> & UPI newswire KSR33 teletypes on a leased loop. > > 33's were uppercase ASCII. I think the wire services used 5 bit machines. > The ones with the type box were 28s. I think the 5 bit code corncob > machine was the 32.The wire services used 5 bit machines, such as the model 15, 19, and 28. The model 15 is what all of us old fogies remember as the intro to US nightly TV news. They always started and ended with a few seconds of model 15 teletype chatter... Walter Cronkite would fill in the time in between. The model 32 was a baudot (5 bit) version of the model 33 ascii machine. It was designed for extremely light duty use, such as a small business would need for Telex duty. For those that don't know, or remember, Telex was to business in the 1970's what the fax machine was to business in the 80-90's
Reply by ●January 8, 20062006-01-08
"Chuck Harris" wrote ...> The wire services used 5 bit machines, such as the model 15, 19, and > 28. > The model 15 is what all of us old fogies remember as the intro to US > nightly > TV news. They always started and ended with a few seconds of model 15 > teletype chatter... Walter Cronkite would fill in the time in between.We would have been better off with 28:30 of TTY SFX. :-) I just heard a radio spot the other day with TTY SFX in the background and the announcer using his best "radio announcer" voice (a parody on news-flash style). It was interesting that the sound of the old TTYs is so anacronistic these days. I was a college freshman running the college radio station solo when they made the mistake and sent the REAL missle attack message over the wire (instead of the regular sunday- morning test tape). That gave us a morning of excitement.
Reply by ●January 8, 20062006-01-08
Richard Crowley wrote:> > "Chuck Harris" wrote ... > > The wire services used 5 bit machines, such as the model 15, 19, and > > 28. > > The model 15 is what all of us old fogies remember as the intro to US > > nightly > > TV news. They always started and ended with a few seconds of model 15 > > teletype chatter... Walter Cronkite would fill in the time in between. > > We would have been better off with 28:30 of TTY SFX. :-) > > I just heard a radio spot the other day with TTY SFX in the > background and the announcer using his best "radio announcer" > voice (a parody on news-flash style). It was interesting that the > sound of the old TTYs is so anacronistic these days. > > I was a college freshman running the college radio station > solo when they made the mistake and sent the REAL missle > attack message over the wire (instead of the regular sunday- > morning test tape). That gave us a morning of excitement.There are two stories I remember coming across the news wire while I was at work in broadcast stations. the first was about a tower collapse at a station that killed most of the tower crew, and just missed the engineer who dived under one of the old RCA broadcast consoles as the tower came through the roof and landed on the console. The other was the murders of "String Bean" (and his wife Ramona) who was a comic on WSM's "Grand Ole Opry". they were robbed and murdered in their front yard because he was known to carry a lot of cash on him, due to his mistrust of banks. -- Service to my country? Been there, Done that, and I've got my DD214 to prove it. Member of DAV #85. Michael A. Terrell Central Florida
Reply by ●January 9, 20062006-01-09
On 6 Jan 2006 13:17:29 -0800, bill.sloman@ieee.org wrote:> Bob Stephens wrote: >> On Fri, 06 Jan 2006 18:54:51 GMT, Roy L. Fuchs wrote: >> >>> On Fri, 06 Jan 2006 18:36:03 GMT, Jonathan Kirwan >>> <jkirwan@easystreet.com> Gave us: >>> >>>>On Fri, 06 Jan 2006 07:35:49 -0700, Jim Thompson >>>><To-Email-Use-The-Envelope-Icon@My-Web-Site.com> wrote: >>>> >>>>>On Fri, 06 Jan 2006 09:46:11 GMT, Robert Baer >>>>><robertbaer@earthlink.net> wrote: >>>>> >>>>>[snip] >>>>> >>>>>> There may still be some devices that will convert RS-232 levels to >>>>>>TTL and some that go the other way. >>>>> >>>>>RS-232 -> TTL = MC1489 >>>>> >>>>>TTL -> RS-232 = MC1488 >>>>> >>>>>These chips are still available more than 40 years after I designed >>>>>them ;-) >>>>> >>>>>These chips adhere to the original RS-232 spec. >>>>><snip> >>>> >>>>1488 requiring several supplies -- and runs hot as a pistol, too. I've >>>>got a box of both; they were about all there was to use in the market >>>>and worked well when I was using them; but don't use them much now >>>>because of the power requirements (especially the 1488) and the >>>>serious heat to be removed (again the 1488 much more than the 1489, if >>>>memory serves, but neither of them slouches in the heating >>>>department.) >>>> >>> >>> Sounds like a poorly implemented utilization. Sum Ting Wong must >>> have done the design. >> >> They always worked well for me - and everyone else in the industry for >> about 20 years... > > The RS-232 specification was originally designed as an interface for > electro-mechanical printers, using discrete transistor logic to convert > signals coming over telephone pair hooked up to the old relay-switched > public telephone system into successive ASCII characters printed on a > rol of paper. > > Search on "Telex" and "TWX". It up-graded the original 50/75 > character-per-second telex system whose only active components were > electro-mechanical - essentially relay logic. > > You should be able to find a history of the ASR-33 terminal somewhere > on the web - that was the cheap version of the ASR-35 bought by people > who had to handle significant amounts of TWX traffic.Nope. The ASR-33 was 20 mA current loop - not RS232. Bob
Reply by ●January 9, 20062006-01-09
On Sat, 07 Jan 2006 07:35:18 -0800, Don Bowey wrote:> On 1/6/06 9:34 PM, in article 43BF5267.24D39FBB@earthlink.net, "Michael A. > Terrell" <mike.terrell@earthlink.net> wrote: > >> Richard Crowley wrote: >>> >>> "Jim Thompson" wrote ... >>>> "techie_alison" wrote: >>>>> "Grant Edwards" wrote ... >>>>>> Charles Jean wrote: >>>>>> >>>>>> Who's Mark? >>>>>> >>>> [snip] >>>> >>>> Space's brother ?:-) >>> >>> ROTFL! :-)) >>> >>> (But likely lost on the younger crowd.) >> >> >> Yeah, they don't know what they missed by never working on the old AP >> & UPI newswire KSR33 teletypes on a leased loop. > > Or the models 14, 15 and 19 that were even before your time. They seemed > hi-tech at the time. My first one at home was a 14 with the range crank on > top, front. It came from a Telco Toll office.Some guy once gave me what I'm almost sure was a "model 13". It used a 60 mA current loop, and ran at "60 WPM" - that's words per minute, where a "word" is five characters. So, five characters per second, and five bits per character, with start and stop bits, that's not very many baud. Back when I was a young stud with an 8008 and .256 KB of RAM, it wasn't that hard to make it type stuff. ;-) Mechanically, it was fascinating. And if you ever get one, don't spray it with WD-40. On a mechanism like a teletype, WD-40 turns to glue. I spent about two weeks with a typewriter brush and isopropyl alcohol cleaning the damn thing up. But it was kewl, toggling stuff into the ol' Scelbi 8H and having the ol' model 13 kachunk it out. :-) Cheers! Rich
Reply by ●January 9, 20062006-01-09
On Fri, 06 Jan 2006 23:44:31 +0000, Charles Jean wrote: ...> I'm the OP of this thread and would like to thank everyone for such a > voluminous and knowledeable response! For those that wanted to know, > the chip is the SV2000 video interface chip from > http://www.speechchips.com. It inputs serial ASCII data and converts > to an RS170 composite video encoded stream. It is supposed to give a > 9 line X 16 character display, with a standard ASCII font as well as > user-defined fonts. Control commands are preceeded by ASCII 27(ESC). > It has been marked down from $20 from $10. I already had a portable > BW TV with a composite video input, so I thought I might try it. By > bit-banging I wouldn't use the precious single UART of my uC, and only > one of its output pins. > > As you can see from the data sheet, the connection on pin 6 allows for > either "normal" or "inverted" TTL levels to be used. I think I could > have saved lots of confusion by rephrasing my question to: "What's the > idling voltage of normal and inverted TTL serial lines?" I can write > the program to have the line at pin 3 idle at either 0 or 5 volts, and > I had a 50-50 chance of having pin 6 wired correctly. Just lazy > again. Sorry if I caused any trouble.Oh, no trouble at all! We like getting into these lively discussions and thread-drift. ;-P Anyway, all I was going to say is try it both ways, especially since you can do it in the micro. Send it some A's and 5's with '0' idle, and see what shows up, and send it some A's and 5's with '1' idle, and see what shows up. At least that's how I'd do it. "RS-232" has always done that to me. :-) Good Luck! Rich
