Instruction Set Architecture (ISA)

Level 2

Machine Level Instruction Set Architecture (ISA):

• This level froms the interface between hardware and software.

• This makes it possible to execute program written in different higher level languages. The programs are translated to ISA level and the hardware can then execute them.


• This, ISA level defines the interface between the compiler and the hardware. It is language that both of them have to understand.

• The higher level programs are compiled to an ISA program. Then this is executed by micro program or hardware.

• An instruction set ,or ISA is a part of the computer architecture related to programming, including the native data type, instructions, registers, addressing mode, memory architecture, interrupt and exceptional handling, external I/O.

• An ISA includes a specification of the set of opcodes, the native commands implemented by a particular CPU design


An operation ADD is a part of instruction set stored in a memory. It is a binary code that tells computer to perform an ADD operation.

• CU decodes instructions from the memory. Then an issue a sequence of control signal to initiate microoperation in internal computer register.

13- Multilevel Viewpoint Of A Machine- ISA


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