Re: (PM) pm3 disconnects

Jon Ribbens (jon@oaktree.co.uk)
Wed, 31 Mar 1999 17:51:19 +0100

pmuser@minbar.taranaki.ac.nz wrote:
> > Hmm, well in ISDN maybe. In the applications I have seen before, the start
> > bit at least is to synchronise the clocks of the sender and receiver.
> > I never quite worked out what stop bits were for.
>
> One of us is suffering from a misconception. My understanding is that start
> and stop bits pertained to asynchronous communications. The start bits are
> used to indicate the start of a character

Well, they do both. The receiver sees the start bit, resets its clock and
prepares to receive a character.

> and the stop bit the end, thus N,8,1 no parity, 1 start bit, 8 data bits.

Why is there any need to 'indicate' the end of a character? It is always
the same length.

> ISDN being a digital service running over a sychronous link would not
> use start or stop bits

It still needs to identify the start of a character, even if it doesn't
need to synchronise the clocks. You don't need a start bit per character
though I guess, you can group the characters into frames.

> unless DOV does.

What is 'DOV'?

Cheers

Jon

-- 
\/ Jon Ribbens / jon@oaktree.co.uk
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