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Re: [RTTY] REAL TTY PICS and SOUNDS and MPGS

To: RTTY Reflector <rtty@contesting.com>
Subject: Re: [RTTY] REAL TTY PICS and SOUNDS and MPGS
From: Kok Chen <chen@mac.com>
Date: Sat, 23 Oct 2004 11:01:27 -0700
List-post: <mailto:rtty@contesting.com>
On Oct 23, 2004, at 5:43 AM, Shelby Summerville wrote:
With all due respect, and my memories of "green keys, etc", aren't
associated with RTTY, but our means of transmitting necessary data, between
cities, when I first started in the airline industry (1964)!

I'll bet you were already using 7 level code rather than 5 level code, Shelby.


My first experience with these guys was with computer input back in 1965. The computer was a Royal Precision Company RPC-4000. The company changed names a couple of times (General Precision was one, if I recall) and then went bankrupt.

The input/output device for said machine was a Frieden Flexowriter. The tape perforator is on the side of the keyboard, so I guess you can classify it as an ASR. Otherwise it just looks like a large electrical typewriter that vibrated like crazy when in action. This Flexowriter read and punched 7 level tape (ASCII) rather than 5 level tape. The carriage of the Flexowriter does move, unlike the later Teletype Corp Model 33 and Model 35 where the carriage does not move, instead the type cylinder moves (the 35 is surprisingly close in appearance to the Model 28 in those pictures, but Teletype Corp had gone to a beige color scheme by then).

With the Model 33 and 35, the print is made with a mechanism that is similar to the IBM Selectrics, except that it is cylindrical instead of spherical. The Selectric typeballs themselves became superseded by Daisy Wheels. On these machines, "carriage return" took on a different meaning from the older machines, but the mechanical settling times for the type heads were still substantial. So we all learned to program in a carriage return before a linefeed since the platten rotation had a much faster settling time than the "carriage."

Paper tape was yet another story. To edit a programming error, you would manually cut sections off of the original tape and splice in a corrected section, like what audiophiles used to do with reel-to-reel audio recording tapes. Later, there were programs such as TECO that would "edit" for you. TECO duplicates an input tape into an output tape up to the point you want an edit made. You then punch the edited part in from the keyboard or memory, the input tape is advanced past the part you are replacing and then the duplication resumes for the rest of the tape. You discard the input tape -- we must have cut down entire forests when writing programs.

Not all "paper" tape was paper, either. The "boot tapes" that are used over and over were punched into mylar tapes. Not all ASR can cut mylar tapes, either. Yes, machines in that era crashed too :-), but more often the rebooting was for when they are taken down for the daily maintenance. I'll bet the mylar tapes would have been great as brag tapes -- any wealthy hams here who had used mylar brag tapes?

73
Chen, W7AY

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