I have seen several systems where it was required to press
the space bar as the first character. In serial communications,
the least significant bit is transmitted first. For a space, the
bit pattern would look like the following:

_________                              ____           _______________
        |                             |    |         |
 Mark   |                             |    |         |
        |_____________________________|    |_________|
             .    .    .    .    .    .    .    .    .    .    .
   1    Start  b0   b1   b2   b3   b4   b5   b6   b7 stop1 stop2  Mark



This conforms to 1 start bit, 8 data bits, no parity and two stop bits.
The processor then has six bits that are low in which to increment a
counter and calculate the serial data rate relative to it's own clock
frequency. The longer time for measurement makes for a more accurate
determination of the serial data rate.

Another example would be to use a ( , 8 , H , X , h or an x. These
characters will allow a measurement for four bits long. Althogh a
little less accurate, you only need to right shift your counter
twice ( divide by four ) in order to calculate your reload data
for your bit counter.

The BASIC interpreter in the 8051AH-BASIC chips requires you to press
the space bar to log on, and then for the real time clock to work,
you give the command xtal = xx.xxxxxx to match the crystal connected
to the micrcontroller.

Hope this help someone,
Jerry