Abstract
- A set of Instruction which contains Opcode & parameters that tells CPU what to do in the form of 0s and 1s. You can check the ISA of a machine using
uname -mp
Portability
The exact hardware implementation of different CPU can vary but app written for a particular ISA like X86 can be run on all the CPU that implements the X86. The ISA functions like a standard that different hardware implementations need to follow, so software has a common interface to work with different CPUs.
Think of the CPU implementation as the logic inside a function, and the ISA specifies the inputs and outputs of the function.
Important
There are two types of ISA, RISC and CISC. Both don’t decide the performance of CPU. CPU Cache and Branch Prediction are two main factors that determine the CPU performance.
“What limits computer performance is predictability” - Jim Keller