Thread: Real-Mode & Protected-Mode
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Old 09-04-2007, 01:31 AM
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This is intel processor specific. In real mode 16 bit cpu can access only 1Mb memory. To get around this problem 80286 and above CPU comes with 2 modes of operation
Real mode
Protected mode – allows to access more than 1Mb memory

By default all modern oses run in protected mode so that you can access 64GB + RAM.

You cannot just move from real to protected mode or vise versa. You need to write a code in assembly language.

Protected mode offers multitasking and stability, memory protection, a paging system, and hardware support for virtual memory. Most modern x86 operating systems run in protected mode, including Linux, FreeBSD, and versions of Microsoft Windows

If you need more information get Intel x86 processor architecture books
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