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Re: Response time

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On Tue, 15 Sep 2015 17:23:52 -0400, Alan Bowler wrote:

> For simple stuff UTS (CP-V) on the Sigma 6 or Sigma 9 had quite amazing
> responce.  Some of the terminals we had were 2741s rented from IBM.  A
> salesman for wanted to sell (or maybe rent) some 2741 clones. (Selectric
> mechanism with non-IBM electronics).  This was a lot cheaper option that
> actual IBM 2741s.  However, they failed when he tried to demonstrate
> them.  (They locked up inputing text.)
> 
> Eventually we figured out what was happening.
> Remember that a 2741 locked the keyboard when you hit CR (sending CR,
> Circle-C).  UTS would recognize this as the end of the input message
> BEFORE the terminal had finished sending the the stop bit of the
> Circle-C.  It would process the input line and send back the prompt for
> the next input (Circle-D, <prompt text>, Circle-C).
> This worked fine with a real 2741 but the clone didn't recognize the
> Circle-D of the prompt because it had not yet finished sending the stop
> bit of its Circle-C.
> Since it didn't recognize the Circle-D, it didn't recognize the rest of
> the message including the Circle-C to unlock the keyboard.

Reminds me of a problem we had with some fairly clunky Perkin-Elmer 
serial terminals (with some screen addressing, so they were generally OK).

The signal for the Shift key 'lagged', so the shift status didn't drop 
immediately you let go of the key. This sometimes meant that if you typed 
a bit fast, the NEXT character was inadvertently shifted. This was a 
trifle annoying, but sometimes catastrophic:

So, there you are, in a development directory on UNIX, and you decide to 
delete all of the object files to clean up (ytes, I know 'make clean' is 
a better approach). So, you type:

  rm *.o

Just think what a 'lagging' Shift key does there....

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Response time Alan Bowler <atbowler@thinkage.ca> - 2015-09-15 17:23 -0400
  Re: Response time Bob Eager <news0005@eager.cx> - 2015-09-15 22:30 +0000

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