Appeal No. 1998-3326 Page 2
Application No. 08/498,819
arbitration judgment is the process of comparing data on the
bus with the
address of, for example, a microcomputer on the bus. Both
processes require strict detection of a start bit across the
bus. If such detection is delayed, arbitration judgment will
not occur during the current machine cycle.
Software and hardware approaches have both been tried to
detect the timing of a start bit issued by a microcomputer on
a data bus. The software approach monitored a bus to detect
when a start bit was issued thereon. Unfortunately, several
machine cycles were required to detect the existence of the
start bit on the bus, which resulted in late detection. The
hardware approach enabled the output of data from a serial
input-output (SIO) register by issuing a start bit to the
register. Unfortunately, timing between the issuance of the
start bit and a clock signal on the bus was asynchronous,
which resulted in a clock pulse cycle delay from the issuance
of the start bit until the output of data from the SIO
register.
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