Two types of data
The CPU is fed long streams of data via the system bus. The CPU receives at least two types
of data:
l Instructions on how to handle the other data.
l Data, which must be handled according to the instructions.
What we call instructions is program code. That includes those messages, which you
continuously send to the PC from the mouse and keyboard. Messages to print, save, open, etc.
Data are typically user data. Think about the letter, which are writing to Aunt Karen. The
contents, letters, images, etc., are user data. but then you say "print," you are sending program
8086 compatible instructions
The biggest job for the CPU consists of decoding the instructions and localizing data. The
calculations themselves are not heavy work.
The decoding consists of understanding the instructions, which the user program sends to the
CPU. All PC CPU's, are "8086 compatible." This means that the programs communicate with
the CPU in a specific family of instructions.
These instructions were originally written for the Intel 8086 processor, which founded the
concept "the IBM compatible PC." The 8086 from 1978 received its instructions in a certain
format. Since there was a desire that subsequent CPU generation should be able to handle the
same instructions which the 8086 could, it was necessary to make the instruction sets
compatible. The new CPU's should understand the same instructions. This backwards
compatibility has been an industry standard ever since. All new processors, regardless of how
advanced, must be able to handle the 8086 instruction format.
Thus, the new CPU's must use much effort to translate the 8086 instruction format to internal
instruction codes:
The CPU is fed long streams of data via the system bus. The CPU receives at least two types
of data:
l Instructions on how to handle the other data.
l Data, which must be handled according to the instructions.
What we call instructions is program code. That includes those messages, which you
continuously send to the PC from the mouse and keyboard. Messages to print, save, open, etc.
Data are typically user data. Think about the letter, which are writing to Aunt Karen. The
contents, letters, images, etc., are user data. but then you say "print," you are sending program
8086 compatible instructions
The biggest job for the CPU consists of decoding the instructions and localizing data. The
calculations themselves are not heavy work.
The decoding consists of understanding the instructions, which the user program sends to the
CPU. All PC CPU's, are "8086 compatible." This means that the programs communicate with
the CPU in a specific family of instructions.
These instructions were originally written for the Intel 8086 processor, which founded the
concept "the IBM compatible PC." The 8086 from 1978 received its instructions in a certain
format. Since there was a desire that subsequent CPU generation should be able to handle the
same instructions which the 8086 could, it was necessary to make the instruction sets
compatible. The new CPU's should understand the same instructions. This backwards
compatibility has been an industry standard ever since. All new processors, regardless of how
advanced, must be able to handle the 8086 instruction format.
Thus, the new CPU's must use much effort to translate the 8086 instruction format to internal
instruction codes:
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