Computer Architecture - Control Unit and Instructions

What is the primary purpose of a computer instruction?

Which of the following is NOT one of the three types of instructions in a basic computer?

In the instruction format for memory reference instructions, what does the 'I' bit indicate?

What is the function of the control register in the instruction execution process?

Which part of a memory reference instruction specifies the actual memory location?

What is the maximum value of Opcode in a memory reference instruction?

What is indicated when the 'I' bit is set to 1 in a memory reference instruction?

How many bits are allocated for the Opcode in a memory reference instruction?

Control Unit Organization

Defines how the control unit supervises and coordinates the operations of the computer.
Essential for executing instructions by translating them into micro-operations.

Basic Concept of Instruction

A program consists of a sequence of instructions that dictate operations and operands for processing.
Each computer instruction is represented as binary code, stored in memory, and read into a control register for execution.
Instructions specify micro-operations that the computer follows for processing tasks.

Instruction Types

Three main types of instructions in a basic computer:
- Memory reference instructions
- Register reference instructions
- Input-output instructions

Memory Reference Instructions

Each memory reference instruction is formatted as 16-bits, consisting of:
- 1 Bit (I) indicating the addressing mode (Direct or Indirect)
- 3 Bits for Opcode, which specifies the operation
- 12 Bits for Address, which identifies the location in memory
Addressing modes:
- I = 0: Direct addressing mode directly uses the address provided.
- I = 1: Indirect addressing mode retrieves the address from another address in memory.
Opcode range is from 000 to 110, allowing for 7 distinct memory reference instructions.

Instruction Format Example

Mnemonic for AND operation:
- Description: AND operation will be executed with the contents of a specified memory location and the Accumulator (AC).
- Instruction code in Hex:
  - For Direct addressing (I=0)
  - For Indirect addressing (I=1)

This quiz explores the organization of the control unit in computer architecture and its role in executing instructions. It covers instruction types, specifically focusing on memory reference instructions and their binary formatting. Test your understanding of how instructions dictate computer operations.