Subject: Re: Unexpected problems, part 2
To: der Mouse <mouse@Rodents.Montreal.QC.CA>
From: Andy Farkas <>
List: port-vax
Date: 05/20/2003 13:52:38
On Mon, 19 May 2003, der Mouse wrote:

> >> {\rant ...breaks...other framing errors...}
> > The problem with this is the fact that most UART chips can't
> > distinguish between the two.  Traditionally, a break is 300ms
> > long...much longer than a byte at even low baud rates.
> 300ms to the byte is 30ms to the bit is about 33 baud.  I've used baud
> rates lower than that, but only for very special purposes (like
> directly driving a light with the signal, for a human to look at).

Isn't the VT100 manual the authorative source?

"BREAK - Typing the BREAK key causes the transmission line to be forced to
its zero state for 0.2333 seconds +/- 10 percent. If either SHIFT key is
down, the time is increased to 3.5 seconds +/- 10 percent. Data Terminal
Ready is also deasserted during this interval. At the conclusion of the
3.5 second interval Data Terminal Ready will again be asserted."

(I keep a "break" key from an original VT100 on top of my monitor because
it looks quite amusing out of context :)

ps. Who's for the return of a "here is" key!! :)



        Andy Farkas
    System Administrator
   Speednet Communications