What is the purpose of the program counter in computer architecture?

The program counter in computer architecture is used to track the address of the next instruction to be executed.

In more detail, the program counter (PC) is a crucial component of the Central Processing Unit (CPU) in a computer. It is a type of register that holds the memory address of the next instruction that the CPU will execute. This is essential for the sequential execution of instructions in a program.

When a computer program is run, the instructions are loaded into the main memory of the computer. These instructions are then executed one by one by the CPU. The program counter keeps track of the execution process by holding the address of the next instruction to be executed. Once an instruction is executed, the program counter is incremented to point to the next instruction.

The program counter is also used during the execution of jump and branch instructions. These instructions alter the normal sequential flow of a program. For instance, a jump instruction may direct the CPU to execute an instruction that is not the next one in sequence. In such cases, the program counter is updated with the address specified in the jump instruction, rather than being simply incremented.

In addition, the program counter plays a vital role during interrupts and subroutine calls. When an interrupt occurs, the current value of the program counter is saved so that the CPU can return to the correct point in the program once the interrupt has been serviced. Similarly, during a subroutine call, the return address is stored in the program counter.

In summary, the program counter is a key component in computer architecture that enables the CPU to execute instructions in the correct sequence. It ensures the smooth and orderly operation of computer programs, and facilitates jumps, branches, interrupts, and subroutine calls.