Basic Operational Concepts of a Computer:

• Most of computer operations are executed in the ALU (arithmetic and logic unit) of a processor.
• For an example: to add 2 numbers that are both located in memory.

-          Each number is taken into the processor, and the definite addition is performed by the ALU.

-          Then sum may be stored in memory or retained in the processor for immediate use.

Registers

• When operands are taken into the processor, they are stored in high-speed storage elements (registers).
• A register may store 1 piece of data (8-bit registers, 16-bit registers, 32-bit registers, 64-bit registers, etc...)
• Access times to registers are quicker than access times to the fastest cache unit in the memory hierarchy.

Instructions

• The Instructions for a processor are declare in the ISA (Instruction Set Architecture)- Level 2
• Typical instructions include following:
• Mov BX, LocA

1.      First fetch the instruction

2.      Fetch the contents of  the memory location LocA

3.      Store the contents in general purpose register BX

• Add AX,BX

1.      Fetch the instruction

2.      Add the contents of registers BX and AX

3.      Place the sum in register AX