
408 THE x86 MICROPROCESSORS
11.3.5.1 | Mode Instruction Format
e mode word, as shown, fi xes up the baud rate, number of characters, and stop bits for trans-
mission. Remember that when the line is idle, it is in the mark (‘1’) state. A start bit is always
low. is should be followed by the data bits and then the stop bits. e insertion of start and
stop bits along with a character, is called ‘framing’. e baud rate is a fraction of the clock
frequency (T × C and R × C are tied together for a link) and the factor can be 1, 16 or 64. If
T × C = 9600 Hz, the baud rate is 9600 bps for a factor of 1 and 9600/16 = 600 for a factor
of 16. ...