Protection in Real Mode
When operating in Real Mode, the IA32 processor does not provide any mechanism to prevent one program from corrupting other programs or data that currently reside in memory. In addition, the currently executing program is permitted to access any IO port directly, rather than going through the OS. For these and other reasons, it would be very difficult to develop a multitasking OS that would run under Real Mode and provide bulletproof protection. Real Mode is intended for use by a single task OS such as DOS.
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