Subject: Re: Behavior of DTR changed between 1.3.3 and 1.4.1???
To: None <firstname.lastname@example.org>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
Date: 10/04/1999 13:51:55
>> I think that Grey Wolf is right here. RS232 was defined for TTL
> RS232 did arrive on the scene at about the same time as TTL, but they
> didn't use the same signal levels.
> "RS-232 was first specified by the EIA in the 1960's" according to
> "RS-232 Simplified" by Byron W. Putman (ISBN 0-13-783499-3, Prentice
> Hall, 1987). ([This] of course [is] not as authoritative as the
> original standards documents, which I wish I had copies of! ;-)
I once got a library to dig up a copy of RS-232C. I don't know about
earlier revs, but the standard I read definitely did not use TTL signal
levels. I no longer have it at hand, but to the extent that my memory
can be relied upon, this paragraph is right:
> Indeed what it all boils down to is that a logic "1" value is
> represented by a voltage between +3 and +25 VDC, and a logic "0"
> value is represented by a voltage between -3 and -25 VDC.
7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B