The Computer The Computer SystemSystem

CS 103: Computers and Application CS 103: Computers and Application SoftwareSoftware

ComputerComputer

Definition An electronic device that accepts

data, processes it, and produces information

Input-->Process-->Output Hardware System Software System

Hardware SystemHardware System

SecondaryStorage

CentralProcessing

Unit

MainMemory

InputDevice

OutputDevice

Hardware SystemHardware System CPU

central processing unit ALU and Control Unit

Main Memory RAM (random-access memory)

-- stores program and data (temporary) ROM (read-only memory)

-- stores basic instructions to the computer (permanent)

Input Device keyboard, mouse, light pen, disk

Output Device monitor screen, printer, disk

Central Processor Unit Central Processor Unit (CPU)(CPU)

Computer’s brain Computer’s brain Execute instructions—e.g., add,

subtract, compare for equality Speed

500 Mhz—500 million instructions per second

1 Ghz—1 billion instructions per second

Main MemoryMain Memory Contains

Program statements to be executed Data to be processed

RAM Transient E.g., application programs 512 MB, 1 GB, 2GB

ROM Permanent Preinstalled E.g., program to accept keyboard input,

to print to screen, to execute statements

MotherboardMotherboard

External StorageExternal Storage

Diskette Diskette Hard Disk Hard Disk CD-ROM CD-ROM DVDDVD USB Flash DriveUSB Flash Drive (pen drive, key (pen drive, key

drive, USB drive) drive, USB drive) TapeTape

Units of StorageUnits of Storage Units of storage

1 Bit (smallest unit of data) 1 Byte = 8 bits (one character) 1 Kilobyte (1000x) 210=1024 1 Megabyte (1,000,000x) 220=1,024,000 1 Gigabyte (1,000,000,000x) 230=1,024,000,000 1 Terrabyte (1,000,000,000,000x)

Storage size Floppy diskette (1.4 MB) CD (600 MB) DVD (4.7 GB Flash memory (200 MB – 4 GB)

Software SystemSoftware System Application Programs

Word processor Spreadsheet Database Management Systems Games

Operating Systems Windows 3.1, 95, 97, 2000, NT Apple Unix, Linux

Programming Language Translators C++ Compiler Java Translater

Network SystemNetwork System

Local Area Network (LAN) Collection of computers connected together

in a limited area to share recourses Share files, programs, printers

Internet World-wide network of computer networks

World Wide Web Collection of Web sites that uses the Internet