Monday, April 27, 2009

INTEL IAPX88 ARCHITECTURE

Now we select a specific architecture to discuss these abstract ideas in concrete form. We will be using IBM PC based on Intel architecture because of its wide availability, because of free assemblers and debuggers available for it, and because of its wide use in a variety of domains. However the concepts discussed will be applicable on any other architecture as well; just the mnemonics of the particular language will be different.

Technically iAPX88 stands for “Intel Advanced Processor Extensions 88.” It was a very successful processor also called 8088 and was used in the very first IBM PC machines. Our discussion will revolve around 8088 in the first half of the course while in the second half we will use iAPX386 which is very advanced and powerful processor. 8088 is a 16bit processor with its accumulator and all registers of 16 bits. 386 on the other hand, is a 32bit processor. However it is downward compatible with iAPX88 meaning that all code written for 8088 is valid on the 386. The architecture of a processor means the organization and functionalities of the registers it contains and the instructions that are valid on the processor. We will discuss the register architecture of 8088 in detail below while its instructions are discussed in the rest of the book at appropriate places.

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