Special-Purpose Registers Used by CPU

The CPU or Central Processing Unit is the brain of a computer system. It is responsible for executing instructions and performing arithmetic and logical operations. To perform these tasks, the CPU uses several registers, which are small, high-speed memory locations within the CPU. These registers are divided into two types: general-purpose registers and special-purpose registers. In this question, we are asked about the special-purpose registers used by the CPU. The correct answer is option 'E', which means all of the following are special-purpose registers used by the CPU:

1. Program Counter (PC):

The program counter is a special-purpose register that holds the memory address of the next instruction to be executed. When the CPU fetches an instruction, it increments the program counter to point to the next instruction in memory. This process continues until the program is complete.

2. Stack Pointer (SP):

The stack pointer is a special-purpose register that points to the top of the stack. The stack is a region of memory used for temporary storage of data during the execution of a program. When a function is called, its local variables are pushed onto the stack. When the function returns, the local variables are popped off the stack. The stack pointer keeps track of the current position of the stack.

3. Instruction Register:

The instruction register is a special-purpose register that holds the current instruction being executed. When the CPU fetches an instruction from memory, it stores it in the instruction register. The instruction register is used to decode the instruction and determine what operation needs to be performed.

4. Memory Address Register:

The memory address register is a special-purpose register that holds the memory address of the data being accessed. When the CPU needs to read or write data from memory, it uses the memory address register to specify the location of the data.

Conclusion

In summary, special-purpose registers are an essential part of the CPU. They are used to hold important information such as the memory address of the next instruction, the top of the stack, the current instruction being executed, and the memory address of the data being accessed. The four special-purpose registers mentioned in the question are Program Counter, Stack Pointer, Instruction Register, and Memory Address Register.