Define Intel 80286 microprocessor. What are the differences between Intel 80186 and Intel 80286 microprocessor?

Subject Microprocessor and Assembly Language
NU Year Set: 5.(c) Marks: 6 Year: 2011

The address unit (AU) computes the physical address what will be sent out to memory or I/O by the BU. The 80286 can operate in one of two memory address modes, real address or protected virtual address mode. If the 80286 is operating in the real address mode, the address unit computes addresses using a segment base and an offset just as the 80286 does. The familiar CS,DS,SS and ES registers are used to hold the base addresses for the segment currently in use. The maximum physical address space in this mode is 1MB, just as 8086.

 If an 80286 is operating in its protected virtual address mode(protected mode), the address unit functions as a complete MMU. In this address mode the 80286 uses all the 24 address lines to access up to 16 MB of physical memory. In protected mode it also provides up to a gigabyte of virtual memory.


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