1.Level of attraction or virtual machine

The function involves in developing programs and in designing the hardware to execute them is so diverse and complex. Computer software and hardware can be view as a series of architectural attraction or virtual machine. For example a high level language (HLL) programmer sees a virtual machine capable of execution instruction while an assembly programmer sees a different machine with registers and memory location that execute specify in assembly language.

2.Translators interpreters emilators and simulators

The commands specify at each attraction level needs to be converted to commands specific to immediate lower level. A translator takes a static program in a lower level exactly once, an interpreter takes individual steps of a program that is been executed (dynamic program) and produce an equivalent sequence of steps in a lower level. A translator is implemented in software while an interpreter is implemented on software or hardware. A software interpreter is mostly called a simulator while a hardware interpreter is called simulator.

Abstraction levels

• Problem definition and modally level architecture
• Algorithm level architecture
• High level architecture
• Assembly  level architecture
• Assembly language, art content of two registers, move memory location
• Instruction set architecture
• Micro architecture
• Interpretation of machine language instructions
• Viewers sees hardware objects such as instruction fetch , interphaces and inter connections

3.Basic processor and memory architecture of a computer system

4.Central processing unit (CPU)

The CPU acts like a brain of a computer and is constituted by the Alu and the CU. It is responsible for control all the operation of all the other units of a computer system ,

-The Alu (arithmetic and logic units) of a computer system is the place where the actual execution of instruction takes place during process

- The control unit (CU): the CU of a computer system manages and coordinates the operation of all other component of the computer system. It fitches and decodes instruction to be executed by the Alu.

5.Register

They are special memory units found in the CPU used to temporally hold information as the cpu interprets and gives instructions. The length of a register (word) equal the number of bits it can store every other parameter being constant. A CPU with 32 bits registers can process data twice larger than with 16 bits registers.

Functions of commonly use registers

6.Calculations of units

The CPU, the memory unit, and the input/output devices which constitute the entire computer system communicate with each other, so are interconnected. The CU and Alu fetch the data from the memory and store it into registers,(working memory), for processing.

7- Interconnection of units

The CPU, the memory unit, and the input/output devices which constitute the entire computer system communicate with each other, so are interconnected. The CU and Alu fetch the data from the memory and store it into registers,(working memory), for processing. After processing, the results are furnished back to the memory via registers, this is made possible by a set of wires which carry groups of bits (information) in a controlled manner as the system bus.