CPU Registers, Instructions, and Bus Systems Explained
CPU Registers: A Deep Dive
Registers are essential for supporting transactions, temporarily storing information to facilitate CPU operations. They are categorized as follows:
- General Purpose Registers: Store data currently in use.
- Segment Registers Memory: Store addresses and data locations.
- Instruction Registers: Monitor the CPU’s status (Flags, overflow, etc.).
Key Registers and Their Functions
- PC (Program Counter): Reads the memory address of the next instruction.
- MAR (Memory Address Register): Acts as a buffer for the program counter, providing the memory address.
- MBR (Memory Buffer Register): Serves as a buffer for writing instructions to memory.
- Acc (Accumulator Register): Stores operands for the arithmetic logic unit (ALU).
- ROP: Contains the opcode for the ALU.
- A: Observes the results of ALU operations.
Timing and Instruction Handling
The Time Builder generates timing signals based on the clock frequency. The Instruction Register (IR) decodes instructions and sends signals for execution.
Address and Memory Spaces
Address spaces are sets of identifiers used by a program, while memory spaces are physical memory locations.
Instruction Sets and Types
Segment instructions are the set of instructions a microprocessor can understand and implement. Types of instructions include:
- Arithmetic: Includes addition and subtraction.
- Logical: Performs operations like AND, OR, and NOT.
- Transfer: Moves data between CPU registers, main memory, and I/O modules.
- Leap: Alters the program counter for jumps, either conditional or unconditional.
- Subroutine Call: Executes specific functions, avoiding routine repetition.
- Input/Output: Transfers data to and from peripherals.
- Specials: Includes instructions like NOP, CLC, and RRC.
Instructions consist of an opcode (operation type) and operands (data being acted upon).
The instruction cycle is the set of actions performed during instruction execution.
The implementation phase involves carrying out all activities related to learning.
Data Bus: A shared pathway for hardware devices to communicate, transferring information within the system.
Control Bus: Manages access to data and address lines, ensuring controlled use of shared components.
The address bus is an independent channel that contains the memory address of data in transit.