4 ms·

I'm a little skeptical. Equipment from this era was designed by slide rule and sent to draftsmen to draw up and send down to the factory floor. The solution to

by jfoutz 5y ago

I'm a little skeptical. Equipment from this era was designed by slide rule and sent to draftsmen to draw up and send down to the factory floor. The solution to problems was more power. I would imagine some wily old programmer knew commands would be latched, and maybe as maintenance fell behind, the CR would lag a little, but could be trusted to complete. Better to do CR LF than LF CR. but they both have to happen. I dunno. Maybe this model sucked. But every teletype I've ever used was kinda scary, those things will take your fingers off. They're power tools capable of violence. I'd guess, if you pulled out the maintenance guide, and applied proper lubrication, and replaced wear parts, it wouldn't miss those deadlines. I guess you might need to pull out the schematic and verify the electronics are still in spec. I mean, yeah, the author has a point, but I'd believe it's a wear issue that this teletype doesn't reliably return in time.

Animats 5y ago
The carriage return time spec for the 5-level teletypes is that CR LF should be sufficient. I've restored two Teletype Model 15 machines, and both work properly with plain CR LF. They're 45 baud, so two characters is 400ms. 8-level, 110 baud devices often needed more time. The early Model 15 teletypes would just overtype at the right margin if you didn't send a CR, and would type on top of the previous line if you didn't send an LF. Mechanical options requiring extra parts were later offered so that overrunning the end of line would force a CR LF. One letter would be typed about halfway across the page, but it was better than losing an entire line because one character was garbled. This was useful for links over shortwave radio, where losing characters was not uncommon. With that feature, CR implied LF. I have two Model 15 machines; one has that feature, the other does not. Too many years ago, I had to overhaul a Teletype driver to handle all the serial devices that appeared just before memory got cheap and everything got buffering. I put in a delay function of the form K1 + linelength*K2. Some serial printers worked with wide paper and needed long delays for their long lines. There was at least one device [1] that needed a negative K2 term. It had a minimum time to print a line, so short lines needed an extra delay. (The early Teletype machines are the dream of the right-to-repair people. Everything is fully documented, all parts are removeable, and they are very repairable. They're also high-maintenance. They need regular oiling, and there are several hundred oiling points and three different lubricants. In heavy use, they need an annual cleaning which involves partial disassembly, soaking in a cleaning bath, and lubrication. They have several hundred adjustments, and a whole "adjustments" manual. Nobody would put up with that today. That's the downside of "right to repair" - the hardware is repairable, but clunky.) [1] http://archive.computerhistory.org/resources/text/DataInterface/Data_Interface.DI-240.1973.102646310.pdf http://archive.computerhistory.org/resources/text/DataInterf...
- romwell 5y ago
  Thanks for the awesome insight! One note: > That's the downside of "right to repair" - the hardware is repairable, but clunky I'd say there is no downside; cause and effect are swapped here. It's that clunky, expensive hardware better be repairable, because the user would rather retain a technician than send the machine in for maintenance (at the cost of time and money). Things that are easily repairable don't have to be clunky or unreliable. Between my bicycles and synthesizers (and music hardware in general), I have dozens of pieces of functional machinery that has lasted decades, and will last for decades to come. That with little maintenance required, and with maintenance being outright pleasant.
- jfoutz 5y ago
  Thank you for the wonderfully detailed reply. I mostly agree with your right to repair sentiments. I have a remote controlled car, and have to keep reminding myself fixing it is half the fun. It sure would be nice to have the option to evaluate repair, either myself or pay a professional, rather than throw things away and buy a new one.

by jfoutz 5y ago

Animats 5y ago

The carriage return time spec for the 5-level teletypes is that CR LF should be sufficient. I've restored two Teletype Model 15 machines, and both work properly with plain CR LF. They're 45 baud, so two characters is 400ms. 8-level, 110 baud devices often needed more time. The early Model 15 teletypes would just overtype at the right margin if you didn't send a CR, and would type on top of the previous line if you didn't send an LF. Mechanical options requiring extra parts were later offered so that overrunning the end of line would force a CR LF. One letter would be typed about halfway across the page, but it was better than losing an entire line because one character was garbled. This was useful for links over shortwave radio, where losing characters was not uncommon. With that feature, CR implied LF. I have two Model 15 machines; one has that feature, the other does not. Too many years ago, I had to overhaul a Teletype driver to handle all the serial devices that appeared just before memory got cheap and everything got buffering. I put in a delay function of the form K1 + linelength*K2. Some serial printers worked with wide paper and needed long delays for their long lines. There was at least one device [1] that needed a negative K2 term. It had a minimum time to print a line, so short lines needed an extra delay. (The early Teletype machines are the dream of the right-to-repair people. Everything is fully documented, all parts are removeable, and they are very repairable. They're also high-maintenance. They need regular oiling, and there are several hundred oiling points and three different lubricants. In heavy use, they need an annual cleaning which involves partial disassembly, soaking in a cleaning bath, and lubrication. They have several hundred adjustments, and a whole "adjustments" manual. Nobody would put up with that today. That's the downside of "right to repair" - the hardware is repairable, but clunky.) [1] http://archive.computerhistory.org/resources/text/DataInterface/Data_Interface.DI-240.1973.102646310.pdf http://archive.computerhistory.org/resources/text/DataInterf...

romwell 5y ago
Thanks for the awesome insight! One note: > That's the downside of "right to repair" - the hardware is repairable, but clunky I'd say there is no downside; cause and effect are swapped here. It's that clunky, expensive hardware better be repairable, because the user would rather retain a technician than send the machine in for maintenance (at the cost of time and money). Things that are easily repairable don't have to be clunky or unreliable. Between my bicycles and synthesizers (and music hardware in general), I have dozens of pieces of functional machinery that has lasted decades, and will last for decades to come. That with little maintenance required, and with maintenance being outright pleasant.
jfoutz 5y ago
Thank you for the wonderfully detailed reply. I mostly agree with your right to repair sentiments. I have a remote controlled car, and have to keep reminding myself fixing it is half the fun. It sure would be nice to have the option to evaluate repair, either myself or pay a professional, rather than throw things away and buy a new one.