What is an ISA?
An ISA, or Instruction Set Architecture, is a written specification that defines the interface between the software and hardware components of a computer system. It defines the set of instructions that a processor can execute and the format of these instructions.
We can view the ISA as an abstraction layer between the hardware and software. This abstraction allows software developers to write programs without having to worry about the underlying hardware implementation details. The ISA provides a standardized set of instructions that software can use to perform operations such as arithmetic, logical operations, memory access, and control flow.
The ISA specifies the format of the instructions, the number and types of operands they can operate on, and the behavior of each instruction. The ISA also defines the registers available in the processor, memory addressing modes, and other architectural features.