1 Introduction to Computers Lect 1 Won’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.

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

3 Information Processing Cycle Input Process Output Storage (Given, ToFind, Method)

4 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.

5 The Primary Hardware Components Of A Computer Input devices. Central Processing Unit (control unit and arithmetic/logic unit). Memory. Output devices. Storage devices.

6 Input Devices Name some…

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

8 Central Processing Unit The 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

9 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

10 Memory -- RAM RAM is volatile --Any information stored in RAM is lost when the computer is turned off. Short term memory.

11 Memory Data in memory is stored as binary digits (BITS) e.g byte = 8 bits 1 byte usually stores 1 text character. 1 nybble is 4 bits

12 Amount Of Memory We measure the size of memory by how many bytes it can store: 1 kilobyte = 2 10 bytes = 1024 bytes 1 megabyte = 2 20 bytes = ~1 million bytes 1 gigabyte = 2 30 bytes = ~1 billion bytes 1 terabyte = 2 40 bytes = ~1 trillion bytes One megabyte can hold approximately 500 pages of text information—a novel.

13 Output Devices Name some…

14 Output Devices Output 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.

15 Storage Devices Name some…

16 Storage Devices Auxiliary (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

17 Hard Disks Permanent storage that is inside of the computer, and NOT portable. Consists of several platters which spin very quickly

18 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.

19 Discs CD-ROM (Compact disc-read only memory), CD-RW (rewritable) DVD-ROM (Digital Video Device) DVD-RW CD can store about 700 MB DVD (Digital Video Device) can store up to 17(?) GB (enough to hold a movie)

20 Flash (Memory) Cards Advantages: Small, easy to carry around High memory capacity – up to 32(?) GB Used in digital cameras, keys and video game consoles.

21 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

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

23 Operating System An 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.

24 Operating System Examples Windows (GUI-Graphical User Interface), Vista DOS MacOS UNIX (Command Line), Linux

25 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)

26 Piano Analogy Piano is hardware Musical score is software Quality of music depends on both Garbage in, Garbage out