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Introduction to Computers

Lect 1Won’t tell you much you don’t know.

(Misleading– the course gets more conceptual as we create webpages.)

Will go into more detail than you care to know in week 9.

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What is a Computer?

A COMPUTER is an electronic device that can: Receive information Perform processes Produce output Store info for future use.

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Information Processing Cycle

Input Process Output Storage (Given, ToFind, Method)

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Hardware vs. Software

Hardware - the physical parts that make up the computer e.g. CPU, memory, disks, CD-ROM drives,

printer. Software - computer programs and

applications. e.g. Operating system, word processor, games,

etc.

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The Primary Hardware Components Of A Computer

Input devices. Central Processing

Unit (control unit and arithmetic/logic unit).

Memory. Output devices. Storage devices.

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Input Devices Name some…

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Input Devices Keyboard. Mouse. Scanner Camera Microphone Barcode reader Digital pad Screen

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Central Processing UnitThe central processing unit (CPU) is the “brain” of the computer. It: Interprets instructions to the computer (CU Control Unit) Performs the arithmetic and logical processing (ALU Arithmetic Logic Unit) e.g. did you enter the correct password Details in week 9

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Memory -- RAM

Main (primary) memory is also called Random Access Memory or RAM. Can randomly access any memory cell directly. It stores: instructions waiting to be executed data needed by those instructions results of processed data

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Memory -- RAM RAM is volatile --Any information stored in

RAM is lost when the computer is turned off.

Short term memory.

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Memory Data in memory is stored as binary

digits (BITS) e.g. 011100101010 1 byte = 8 bits 1 byte usually stores 1 text character. 1 nybble is 4 bits

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Amount Of MemoryWe measure the size of memory by how many bytes it can store:1 kilobyte = 210 bytes = 1024 bytes1 megabyte = 220 bytes = ~1 million bytes1 gigabyte = 230 bytes = ~1 billion bytes1 terabyte = 240 bytes = ~1 trillion bytesOne megabyte can hold approximately 500 pages of text information—a novel.

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Output Devices Name some…

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Output DevicesOutput devices make the information resulting from the processing available for use. printer - produces a hard copy of your output screen - produces a soft copy of your output speakers, plotter, etc.

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Storage Devices Name some…

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Storage DevicesAuxiliary (Secondary) memory: storage devices are used for permanent (longterm) storage. hard disks floppy disks compact discs – CD and DVD flash (memory) cards magnetic tape - sequential

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Hard Disks

Permanent storage that is inside of the computer, and NOT portable.

Consists of several platters which spin very quickly

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Floppy Disks – 1.44 MB

A floppy disk is a portable, inexpensive storage medium that consists of a thin, circular, flexible plastic disk with a magnetic coating enclosed in a square-shaped plastic shell.

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Discs CD-ROM (Compact disc-read only memory), CD-RW (rewritable) DVD-ROM (Digital Video Device) DVD-RWCD can store about 700 MBDVD (Digital Video Device) can store up to

17(?) GB (enough to hold a movie)

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Flash (Memory) Cards

Advantages: Small, easy to carry around High memory capacity – up to 32(?) GBUsed in digital cameras, keys and video game

consoles.

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Software A program is a sequence of instructions for

the computer to carry out in order to complete a task.

Analogous to a recipe which is a sequence of instructions for a cook or directions for a driver.

The comuter executes one instruction at a time

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Software

Software can be categorized into two types: System software Application software.

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Operating SystemAn operating system is a computer program

that manages the computer. Controls how the hardware components of

the computer (CPU, memory, and I/O devices) work together.

Organizes and manages files and directories Enables you to communicate with the

computer.

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Operating System Examples Windows (GUI-Graphical User

Interface), Vista DOS MacOS UNIX (Command Line), Linux

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Application Software

Application Software is a program that performs a particular task. Some of the more common software packages are: Word processing Electronic spreadsheet Database Presentation graphics (like this Powerpoint)

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Piano Analogy Piano is hardware Musical score is software Quality of music depends on both

Garbage in, Garbage out