Overview of Computer Hardware

• Central Processing Unit
• Memory
• Input/Output Devices

Memory

A Large Ordered Collection of Bits

• Byte (8 bits)
• MSB, LSB
• Word
• 8086 two bytes
• Double Word
• Quad Word

• kilobyte
• 2¹⁰ bytes
• 1,024 bytes
• megabyte
• 2²⁰ bytes
• 1,048, 576 bytes
• gigabyte
• 2³⁰ bytes
• 1,073, 741, 824 bytes

Each byte in memory is associated with an Address

CPU -- Brain of the computer

• Control Unit (CU)
• Fetch the Instruction at the memory location pointed to by the Instruction Pointer
• Update the Instruction Pointer to point to the next instruction
• Execute the previously fetched instruction
• Arithmetic/Logic Unit (ALU)
• Performs arithmetic, logical, and relational operations
• Registers
• Very fast memory cells used by the CPU in carrying out instructions

Registers

• 4 General Purpose Registers
• AX (Accumulator)
• BX (Base)
• CX (Counter)
• DX (Data)
• Instruction Pointer (IP)
• Stack Pointer (SP)
• Flags Registers