IPC144 Introduction to Programming Using C Instructor: Travis Mander 1

Introduction to Computer Programming Computer Organization 2

Objectives: By the end of this session, the student will be able to: Name and define 5 categories of Computer Architecture Show how these categories inter-relate Define the function of input devices Define the function of output devices Define the function of Primary Storage Distinguish between addresses and data List the two parts of the CPU Describe the function of each part of the CPU Define the function of Secondary Storage Describe the interaction between: Hardware Operating System Application Software User 3

Computer Architecture The architecture of a computer can be broken down into 5 categories. These 5 categories interrelate with each other in a structured way. Categories The categories of the architecture of a computer system are: 4

Computer Architecture, Continued Interrelation of Categories The categories interrelate in the following way: 5 Input Primary Storage Secondary Storage Output ©

Input Purpose The purpose of input is to take data that is external to the computer system, and transform it into data that is internal to the computer system. Some of the devices that perform this function are: Keyboard Mouse Barcode scanner Optical Mark Recognition (OMR)‏ Optical Character Recognition (OCR)‏ Hand-written characters Voice recognition Touch screens 6

Output Purpose The purpose of output is to take information that is internal to the computer system, and transform it into information that is external to the computer system, and therefore available for the user to use. Some of the devices that perform this function are: Monitor Dot-matrix printer Bubble-jet printer Laser printer Voice (Audio)‏ 7

Primary Storage Purpose The purpose of primary storage is: to store software that is in the process of being executed to store data for a short period of time while it is being manipulated The term 'memory' is also used when referring to Primary Storage. There are two types of Memory: RAM - Random Access Memory ROM - Read Only Memory ROM is read only memory, its contents cannot be altered, therefore is not Primary Storage. Unless otherwise stated, when we refer to memory in this course we are referring to RAM. 8

Primary Storage, Continued Addresses and Data Memory - a long street with millions or billions of houses Each house has an address - a number Each house has an occupant - a piece of data which is represented by a number from 0 to 255 Sometimes all it takes is a single house to represent something, such as single character (a letter of the alphabet). Sometimes many houses get together to represent something, For example it takes four houses to represent a single precision floating point number 9

Primary Storage, Continued Addresses and Data MB of RAM is a street with 134,217,728 houses (addressed ,217,727)‏ 72 (H) 105 (i)

Processor Purpose The processor, or Central Processing Unit (CPU) is where the computer system performs the manipulation of data. Every computer must have at least one CPU to function. A processor is composed of: Control unit Arithmetic / logic unit (ALU)‏ Control unit The control unit oversees the operation of the CPU by performing: Fetch - get an instruction from memory Decode - decide what the instruction means and direct the necessary data be moved from memory to the ALU The combination of Fetch and Decode is called, Instruction Time or I-Time 11

Processor, Continued Arithmetic / Logic Unit The ALU performs two classes of operations: Arithmetic operations Logical operations The ALU is responsible for: Execute Store The combination of Execute and Store is call Execution-Time, or E-Time 12

Processor, Continued Arithmetic operations The arithmetic operations performed by the ALU are: Addition Subtraction Multiplication Division Older ALUs could only perform addition and subtraction. The multiplication and division operations were performed through a set of instructions. 13

Processor, Continued Logic operations The logic operations, or tests, performed by the ALU are: Equal-to Greater than Less than These can be combined to create an additional three tests: Greater than or equal Less than or equal Greater than and Less than (not equal)‏ 14

Processor, Continued Machine cycle A machine cycle is the combination of I-Time and E-Time. The I-Time and E-Time differs from instruction to instruction, therefore the machine cycle will also be different. Diagram of a machine cycle This a diagram of the steps in a machine cycle: 15 Control Unit Arithmetic / Logic Unit 2 - Decode 1 - Fetch Memory 3 - Execute 4 - Store

Secondary Storage Purpose The purpose of secondary storage is to: retain data and programs while the computer system is turned off hold data and programs that cannot fit into primary storage Types of secondary storage Secondary storage is composed of two main groups of media, within each group are many types of secondary storage. The most common are: Magnetic media floppy diskette tape hard disk Optical media CD-ROM / -R / -RW DVD-ROM / -RAM 16

Computer Architecture Layers of the computer The computer is structured in layers, conceptually can be thought of: 17 Hardware Operating System Application User

Computer Architecture Layers of the computer Advantages: Simplified interface for each layer (user does not need to know how to trigger an interrupt to start reading from the disk drive). Change of hardware does not necessarily mean a change to the Applications - maybe just the O/S We are concerned with the Application layer- we must interface to the User and the Operating System The 'gap' allows the User to request certain tasks of the O/S (which application to launch, format a diskette, backup system...)‏ 18 Hardware Operating System Application User