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Processor Modes

flint.cs.yale.edu · 961 words · saved by 1 readers

Processor modes refer to the various ways that the processor creates an operating environment for itself. Specifically, the processor mode controls how the processor sees and manages the system memory and the tasks that use it. There are three different modes of operation, that resulted from the evolution of the PC from its humble beginnings with the Intel 8088 chip. Real Mode: The original IBM PC could only address 1 MB of system memory, and the original versions of DOS created to work on it were designed with this in mind. DOS is by its nature a single-tasking operating system, meaning it can only handle one program running at a time. The decisions made in these early days have carried forward until now, and in each new processor, care had to be taken to be able to put the processor in a mode that would be compatible with the original Intel 8088 chip. This is called real mode. When a processor is running in real mode, it acts like an "8088 on steroids". What this means is that it has

Processor Modes Processor Modes Processor modes refer to the various ways that the processor creates an operating environment for itself. Specifically, the processor mode controls how the processor sees and manages the system memory and the tasks that use it. There are three different modes of operation, that resulted from the evolution of the PC from its humble beginnings with the Intel 8088 chip. Real Mode: The original IBM PC could only address 1 MB of system memory, and the original versions of DOS created to work on it were designed with this in mind. DOS is by its nature a single-tasking

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