Computer Engineering Rabie A. Ramadan Lecture 1

2 Welcome Back

Organization of the Course 3 Two Lectures weekly Evaluation is based on: Midterm and Final Exams Assignments In class group activities  almost every lecture

Organization of the Course (Cont.) 4 Textbooks Mostafa Abd-El-Barr and Hesham El-Rewini, Fundamentals of computer Organization and architecture, Wiley interscience, 2005.

Class Rules 5 Attendance is a mandatory Assignments must be delivered on time Assignments must be submitted in electronic format  no papers will be accepted

Things need to be with you in class 6 For the group activities

Before we start …. Lets have a group activity for 2 minutes

Game No. 1 Study the circles below. Work out what number should replace the question mark.

9 Hit 4 * 5 + 3* 6 = 38 8 * * 5 = 47

Video Part 10 Play What does it tell you? Be Smart and Think Smartly

Table of Contents Introduction Historical Development Computer Hierarchy The Von Neumann Model Architecture Development and Styles

Introduction Computer Architecture : Focuses on the structure and behavior of the computer system Refers to the logical aspects of system implementation as seen by the programmer. How do I design a computer? Computer Organization: Focuses on the relationship exists between computer hardware and many aspects of programming and software components in computer systems. How does a computer work?

Introduction It is not easy to separate computer organization issues from computer architecture issues due to: Principle of Equivalence of Hardware and Software Anything that can be done with software can also be done with hardware, Anything that can be done with hardware can also be done with software. A computer is a device consisting of three pieces: A processor to interpret and execute programs A memory to store both data and programs A mechanism for transferring data to and from the outside world

Main Components of a Computer (Cont.) Human being brain  Processor Writing notes  saving data in the memory Pencil or pen used to write is the I/O mechanism

Computer Development and Moore's Law New devices are invented almost every day Technology became smaller and smaller Millions of transistors on a chip. Where it ends ? How small can we make transistors? How densely can we pack chips?

Computer Development and Moore's Law (Cont.) In 1965, Intel founder Gordon Moore stated, "The density of transistors in an integrated circuit will double every year." The current version of this prediction is usually conveyed as "the density of silicon chips doubles every 18 months." Moore's Law cannot hold forever. Moore intended this postulate to hold for only 10 years There are physical and financial limitations that must ultimately come into play.

Computer Level Hierarchy

Computer Level Hierarchy (Cont.) Level 6 (the User Level): Composed of applications and is the level with which everyone is most familiar. Examples: Word, graphics, and games. Level 5 (The High-Level Language Level): Languages such as C, C++, FORTRAN, Lisp, Pascal, and Prolog. Level 4(the Assembly Language Level): compiled higher-level languages are first translated to assembly, which is then directly translated to machine language. Level 3 (the System Software Level) deals with operating system instructions. responsible for multiprogramming, protecting memory, synchronizing processes, and various other important functions

Computer Level Hierarchy (Cont.) Level 2 (Instruction Set Architecture (ISA) or Machine Level) The machine language recognized by the particular architecture of the computer system. Level 1(Control Level) Where a control unit makes sure that instructions are decoded and executed properly and that data is moved where and when it should be. Level 0 (Digital Logic) Computer Hardware

The Von Neumann Model The system passes all of its I/O through the arithmetic logic. It uses von Neumann execution cycle (also called the fetch- decode-execute cycle)

The Von Neumann Model (Cont.) A cycle could be as follows: 1. The control unit fetches the next program instruction from the memory, using the program counter to determine where the instruction is located. 2. The instruction is decoded into a language the ALU can understand. 3. Any data operands required to execute the instruction are fetched from memory and placed into registers within the CPU. 4. The ALU executes the instruction and places the results in registers or memory.

Instruction Processing Von Neumann execution cycle Decode instruction Evaluate address Fetch operands from memory Execute operation Store result Fetch instruction from memory

The Modified Von Neumann Model The data bus: Moves data from main memory to the CPU registers (and vice versa). The address bus: Holds the address of the data that the data bus is currently accessing. The control bus: Carries the necessary control signals that specify how the information transfer is to take place. Did we gain something ?

Architecture Development and Styles Performance is the main goal of any architecture Complex instructions Reduces the number of instructions to be used Small number of instructions to perform a job. Using different addressing modes that fits the required task Examples : Complex Instructions Set Computers (CISCs) such as : Intel PentiumTM, Motorola, MC68000TM, and the IBM & Macintosh PowerPCTM.

Architecture Development and Styles (Cont.) Speeding up some of the effective instructions More than 80% of the instructions executed are those using: Assignment statements, conditional branching and procedure calls. Simple assignment statements constitute almost 50% of those operations. Optimizing such instructions enhances the performance Example: Reduced Instructions Set Computers (RISCs) such as: Sun SPARCTM and MIPS machines.