Click above to get retro games delivered to your door ever month!

 Protected mode
------------------------------------------------------------------------------
 Protected mode refers to the enhanced mode of the 80286 and above. These
 processors were designed with backwards compatibility as being of primary
 importance, but with the need to extend the address space beyond 1 Mb.
 When these processors are powered up they start running in 8086 mode, known
 as real mode, and in the absence of any special software will continue to
 run as an 8086, only with better performance due to their increased clock
 speeds and reduced instruction execution times.

 Specific software instructions may be used to switch the processor into one
 of its enhanced modes at any time, at which point the processor starts to
 function as a more advanced processor with a number of extra capabilities,
 including the ability to access more than 1 Mb of memory. The processor may
 be switched in and out of protected mode at any time if required, although
 the 80286 requires a significant amount of time (milliseconds) each time a
 switch to protected mode is requested.

 When running in 80286 protected mode, rather than interpreting the segment
 as an absolute memory address the processor interprets it as an index into a
 look up table which contains 24 bit physical base addresses for all the
 memory segments in the system. Using this 24 bit base address and a 16 bit
 offset allows the processor to address 16 Mb of physical memory. The memory
 is still segmented, however, with the largest segment being 64 Kb.