[GreenKeys] shockingly basic question - Teletype Model 33 ASR

[Mike Douglas]

 Early microcomputers, which relied heavily on the Model 33 as an operator's console, included the option for following CR with one or more null characters (ASCII zero) to give time for the print head to reach the left margin. Typically one null was plenty. A null prints nothing and engages no function bars.

Unrelated to TTY operation, the extra null also ended up on the paper tape when saving a program. When subsequently loading that tape, the null gave the BASIC interpreter an extra 100ms to process the line just received before more data came in (i.e., the NULL was lost but didnt matter).

Mike

     On Friday, February 5, 2021, 12:07:15 AM CST, Dave Horsfall <dave at horsfall.org> wrote:  
 
 On Thu, 4 Feb 2021, WAYNE wrote:

> Mike is correct.  A 33 needs time for all its functions.  On a CR LF its 
> important that they be in that order and even then the carriage has just 
> barely enuf time to return from a full line.  If you want to be sure use 
> CR, LF, Delete or Rubout as well and 2 stop bits from the computer.

I've been told that CR CR LF is best, as it has no side-effects.

-- Dave, still pondering over his iPad RTTY program______________________________________________________________
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