• Time-sharing:When one module is controlling the bus, other modules are locked
out and must, if necessary, suspend operation until bus access is achieved.
These uniprocessor features are directly usable in an SMP organization. In this
latter case, there are now multiple processors as well as multiple I/O processors all
attempting to gain access to one or more memory modules via the bus.
The bus organization has several attractive features:
• Simplicity: This is the simplest approach to multiprocessor organization. The
physical interface and the addressing, arbitration, and time-sharing logic of
each processor remain the same as in a single-processor system.
• Flexibility: It is generally easy to expand the system by attaching more processors
to the bus.
• Reliability: The bus is essentially a passive medium, and the failure of any
attached device should not cause failure of the whole system.