Question about serial interface

FENN CORWIN HO MING (cfenn@ece.ubc.ca) Thu, 13 Apr 2000 12:19:53 -0700 (PDT) 

Date: Thu, 13 Apr 2000 12:19:53 -0700 (PDT)
From: FENN CORWIN HO MING <cfenn@ece.ubc.ca>
Subject: Question about serial interface




1) How can we distinguish a start bit and a stop bit
   from the bits of the data being transfer?

   From the lecture note, it says that the start bit
   and stop bit are longer (1.5 bit) than the data bits.
   It that right?  If so, what is the answer for question
   #5 c) in the past final exam (98/99 winter term2) which
   says:

   (c) Which of the following changes to the transmission
       format of ASCII characters over an RS-232 serial
       interface would not change the characters received?

        1. Using two start bits?
        2. Using two stop bits?