The full form of ISA is International Standard Architecture.

Explanation:
The International Standard Architecture (ISA) is a specification that defines the internal architecture of a computer's central processing unit (CPU). It describes the organization, functionality, and capabilities of the CPU, including its instruction set architecture, memory architecture, and input/output architecture.

- ISA is a set of rules and standards that govern the operation of a CPU. It defines the format and meaning of instructions that the CPU can execute, as well as the organization and configuration of its registers and memory.

- The instruction set architecture is the set of instructions that a CPU can understand and execute. It defines the operations that the CPU can perform, such as arithmetic, logical, and control operations. The instruction set architecture also specifies the format of instructions and the addressing modes used to access data in memory.

- The memory architecture of a CPU defines how it accesses and manages memory. It specifies the types of memory supported by the CPU, such as cache, main memory, and virtual memory, as well as the addressing modes used to access memory locations.

- The input/output architecture of a CPU defines how it communicates with peripheral devices, such as keyboards, displays, and storage devices. It specifies the protocols and interfaces used for input and output operations, as well as the addressing modes used to access peripheral devices.

- The ISA is an important component of computer architecture because it provides a standardized interface between the hardware and software layers of a computer system. It allows software developers to write programs that can run on different CPU architectures, as long as they conform to the same ISA.

- The International Standard Architecture (ISA) is not to be confused with the Industry Standard Architecture (ISA), which is an older bus architecture used in early IBM-compatible personal computers. The ISA bus is no longer in common use, but the term ISA is still used to refer to the instruction set architecture of a CPU.