The Computer System CS 103: Computers and Application Software

Computer Definition An electronic device that accepts data, processes it, and produces information Input-->Process-->Output Hardware System Software System

Hardware System Secondary Storage Central Processing Unit Main Memory Input Device Output Device

Hardware 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 (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 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

Motherboard

External Storage Diskette Diskette Hard Disk Hard Disk CD-ROM CD-ROM DVD DVD USB Flash Drive (pen drive, key drive, USB drive) USB Flash Drive (pen drive, key drive, USB drive) Tape Tape

Units of Storage Units of storage 1 Bit (smallest unit of data) 1 Byte = 8 bits (one character) 1 Kilobyte (1000x) 2 10 = Megabyte (1,000,000x) 2 20 =1,024,000 1 Gigabyte (1,000,000,000x) 2 30 =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 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 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