Single bus architecture: In a uniform memory access multiprocessor, any memory word in the multiprocessor can be read in the uniform speed. Below given is a UMA multiprocessor with single bus architecture. Here n number of CPUs can be connected to a single bus. In this type of architecture the maximum n umber of CPUs that can be connected is 32. That means the maximum value of n can be 32. Private memory is reserved for a particular CPU and it is private to that CPU. Other CPUs cannot access it. Private memory is used for storing read only data, stacks, text, strings, constants, and local variables. Shared memory is used for storing write only shared variables. Cache is also local to a particular CPU which is used for improving performance.
Using crossbar switch: By using a crossbar switch, any number of CPUs can be connected with a single bus. A cross bar switch can be opened or closed by using an electrical signal. When a crossbar switch is used connections can be made easily to the CPUs.