PLEX86  x86- Virtual Machine (VM) Program
 Plex86  |  CVS  |  Mailing List  |  Download  |  Computer Folklore

what's the difference between LFLine Fee and NL New line 4450


What is bizarre is that while the designers of UNIX saw the long understood advantage, others didn't and apparently in simple ignorance used a different convention.

Of course the actual concept of using LF for a newline, rather than requiring both LF and CR, goes *way* back... to Teletype machines much older than the Model 37 and long before UNIX.

I don't understand what that was supposed to mean.

Even the delay goes much farther back than UNIX.

what's the difference between LFLine Fee and NL New line 4453
local connected 3270 were significantly faster (hundreds of kbytes-sec) ... however interactions were half-duplex and the keyboard...

Before the Model 28 (which had a type box that moved), the Model 15 Teletype used a type basket (much like the old typewriters) and the paper platen moved. A CR cause this *huge* and *heavy* platen to go all the way to one edge. If it did that from the far end, this was an earth shaking event (well, at least it could shake a whole building). And a time consuming event.

Whatever, because a missed CR or LF would result in unreadable garble, it was very common to mechanically configure Teletype machines to do only a CR on CR, but to do first a CR and then an LF when an LF was received. And the typical way that either tapes were cut or that operators manually typed was to send CR, then LF, and then a LTRS character one or more times. That would give the carriage 3 or 4 character time intervals to correctly position itself. For "five level Baudot" code, which sends 7.5 bits per character, a 60 wpm (45.5 baud) machine would take 165ms per character, so a three character delay would be half a second.

A LTRS character was all of the holes in the tape punched. Most machines were configured to return to Letters mode (as opposed to Figures) when a newline was sent, but by sending a LTRS that ensured that the results would be the same on any machine.

The LTRS character was also used to "correct" errors on a tape (just back up the tape and punch all the holes over the error and then retype it correctly) and to splice tapes (which was very easy with "chadless" punches).

Teletype machines on the other hand (until the more recent ones) were designed to run 24-7. Model 15 and Model 28 machines were used by news services, and simply worked. The Model 37 wasn't as sturdy, but it was certainly what could be called reliable. But Teletype also produced the low cost model 32-33 machines beginning in the early 1960s, which did not match previous models for reliability.

what's the difference between LF Line Fee and NL New line
With Teletype machines (e.g., model 15 and model 28) in the days when most Teletype circuits ran at 45.5 baud (60 wpm), the keyboard provided feedback to set a rhythm for the...

--


List | Previous | Next

what's the difference between LF Line Fee and NL New line

Alt Folklore Computers Newsgroups

what's the difference between LFLine Fee and NL New line 4449