Memory_Reference_Instructions. Computer architecture

Memory_Reference_Instructions. Computer architecture

• 1.
  Memory Reference Instructions ComputerArchitecture
• 2.
  What are MemoryReference Instructions? • - Instructions that access main memory (RAM) • - Operands may be in memory, not just registers • - Used for data transfer, arithmetic, logic, and control
• 3.
  General Instruction Format •[ Opcode | Address ] • - Opcode: Specifies the operation (e.g., LDA, STA, ADD) • - Address: Memory location of operand
• 4.
  Examples of MemoryReference Instructions • 1. LDA → Load Accumulator from memory • 2. STA → Store Accumulator into memory • 3. ADD → Add memory content to Accumulator • 4. SUB → Subtract memory content from Accumulator • 5. AND / OR → Logical operations with memory • 6. BUN → Branch Unconditionally
• 5.
  BUN (Branch Unconditionally) •- Control transfer instruction • - Operation: PC ← Address • - Always branches (no condition) • - Skips sequential execution • - Example: • 101: BUN 300 → PC jumps to 300 • 102 is skipped
• 6.
  Uses of BUN •- Change program flow • - Create loops or infinite jumps • - Jump to subroutines (with BSA) • - Useful in control and decision-making