From: atbowler AT thinkage DOT on DOT ca (Alan Bowler)
Newsgroups: comp.os.msdos.djgpp,comp.os.cpm,alt.folklore.computers
Subject: Re: EOF char.  (Was C++ and RHIDE)
Date: 6 Jul 1998 17:32:33 GMT
Organization: Thinkage Ltd.
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References: <35a4cd9e DOT 28052267 AT news5 DOT bellatlantic DOT net> <35a4c1be DOT 23702950 AT news DOT innet DOT be> <359FFF58 DOT 71CE272E AT alcyone DOT com>
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In article <359FFF58 DOT 71CE272E AT alcyone DOT com> Erik Max Francis <max AT alcyone DOT com> writes:
>Luc Van der Veken wrote:
>
>> What exact character would be used in the papertape days to
>> signal the end of a tape? Decennia ago I used them, but I don't
>> remember.
>> 
>> CTRL/Z - ETX (CTRL/C) - EOT (CTRL/D) - EM (CTRL/Y)?
>> 
>> Or more than one, platform-dependent?
>
>EOT (0x04, ^D) is the "correct" one from the ASCII standard, since it
>stands for "end of transmission."  This is used (almost?) universally on
>Unix systems, 

That does not make it correct.  EOT had a particular function.
It powered down the teletype to a standby state.  The motor would
stop turning, and so on real teletypes that mechanically did the
serial decode this meant that the teletype could not even interpret
characters on the line.  The other end would wake up the teletype
(start the motor running again) by sending a "long break"

The "correct" choice for end of file, was File Separator (FS,
control-backslash), but Gcos is the only system I know that used that.

Generally paper tape stuff didn't much use "end of file".
A tape would be prepared with a set of chunks each ended by 
X-OFF (DC3, ctrl-S).  The machine would send out X-ON (DC1 ctrl-Q)
to start the paper tape reader going, and the reader would stop
when it read the next X-OFF.  Alternately, the machine use a timeout
mechanism to decide when there was no more paper tape.