what is program counter

A program counter (PC) is a register in a computer processor that contains the memory address of the instruction being executed at the current time. It is a fundamental component of a computers central processing unit (CPU) and indicates where a computer is in its program sequence. The PC is incremented after fetching an instruction and holds the memory address of the next instruction that would be executed. The PC is a digital counter that may be one of several hardware registers in a simple CPU. The instruction cycle begins with a fetch, in which the CPU places the value of the PC on the address bus to send it to the memory. The memory responds by sending the contents of that memory location on the data bus. The PC can be modified by certain instructions or events during program execution, such as branching instructions that can change the program counter to redirect the flow of execution to a different part of the program. In multitasking operating systems, the program counter plays a crucial role in context switching between different tasks or processes. If the program counter gets corrupted or lost, the CPU would lose track of the next instruction to execute, leading to a program malfunction or crash. The program counter is not specific to a particular programming language and exists at the hardware level in the CPU.