Unit 1A - Computer Basics

A computer is a device that

  • Accepts input
  • Processes data
  • Stores data
  • Produces output
  • Uses a series of stored instructions

Computers process data based on a series of storedinstructions in a storedprogram

Stored instructions

  • provide a very flexible approach to processing data
  • make a computer different from most other devices

Data vs. Information - Information is data in a format that has meaning to people

Storage – a long term place to keep data that may be needed for future processing

Storage includes

  • Hard disk
  • floppy disk
  • CD
  • DVD
  • flash memory

Memory – a temporary place for data currently being processed, workspace for tasks

Processor – manipulates data in memory according to instructions in a stored program

Peripherals – other devices that add functionality such as a printer or scanner

System Unit – holds processor, memory, storage devices, etc

Categories -

  • Personal computer - designed to be used by one person at a time
  • 3 basic types – desktop, notebook, and tablet
  • Mainframe – designed to be used by many people at one time
  • Larger and more expensive than personal computers
  • Can serve a large number of dumbterminals
  • Used by larger businesses
  • Supercomputer – extremely fast, designed for highly complex problems
  • Server – supplies data to other computers on a network
  • Client – a computer that receives data from a server
  • Personal Electronic Devices – limited function handheld devices
  • PDA’s, cell phones, MP3 players, etc.

Application software – carries out a task for a user

System software – controls activities and functions of a computer

provides a computer with a basic level of functionality

Compatibility – also called platform, is determined by processor and operating system

Unit 1B – Files and File Management

File – (as it relates to computers at least) a named collection of data on a storage medium

  • Only storage devices (hard disk, floppy, CD, etc) hold named collections of data
  • Although RAM holds data it does not store it as a named collection

Storage media – the actual recording surface such as a CD, DVD, or flash memory

Storage device – the mechanical device that stores or retrieves data from the medium

Data File – anything that provides information to a user when properly formatted

  • Examples are text, music, pictures, video, etc.

Executable File – a stored program or series of instructions on how to perform a task

File Name Extensions – provide information as to the contents and format of a file

Common file name extensions for Microsoft Office are:

  • Word.doc.docx
  • Excel.xls.xlsx
  • PowerPoint.ppt.pptx
  • Access.mdb.accdb

The operating system recalls the file size, the date created, and date last changed

File sizes are expressed in bytes

A byte is the storage required (8 bits) to represent a single character

The term byte is typically prefaced by the following:

  • Kilo – meaning approximately one thousand
  • Mega – meaning approximately one million
  • Giga – meaning approximately one billion

Know the file naming rules for Windows

  • File name and extension cannot exceed 255 characters
  • Spaces allowed
  • Numbers allowed
  • Some characters have special meaning and are not allowed such as * / : \ < > ? |
  • Some names such as Aux, Com1, Com2, Lpt1, Lpt2, Prn have special meaning and are not allowed but can be used as PART of a file name

Drive letters:

  • Floppy drive is always referred to as A:
  • The main hard disk is always referred to as C:
  • The CD/DVD drive is usually but not always referred to as D:
  • After the main hard drive D:, drive letters are unpredictable & assigned as needed

Folders:

  • The term folder, directory, subfolder, and subdirectory are used interchangeably
  • All storage devices have a main directory, called the root directory
  • The root directory is indicated by a single backslash such as C:\
  • Everything springs from the root directory which can contain files or folders
  • Any folder can be divided into subfolders by creating a folder within a folder

Be sure to understand the file specification example

  • Be able to identify the drive letter, primary folder, subfolders, filename, extension
  • Understand that:
  • a colon separates the drive letter from the rest of the file spec
  • a backslash separates folders
  • the final backslash separates the filename from the folders
  • a period separates the file name from the extension

A file’s exact location is completely described by its file specification (aka the file’s path)

Understand how to use folders and subfolders to organize your storage like a file cabinet

Windows Explorer & My Computer are operating system supplied file management tools

Windows Explorer has a right pane and left pane

  • Left pane shows the storage devices & folder structure but no files
  • Left pane hierarchical file/folder structure display is similar to a tree on its side
  • Right pane shows the files and folders in the currently selected folder
  • Windows Explorer is more usefulwith its left pane device/folder structure display
  • Clicking on a left pane plus sign displays subfolders for that device/folder
  • Clicking on a left pane minus sign collapses the subfolder display
  • Clicking on a left pane device/folder displays its files/folders in the right pane
  • Double clicking on a right pane folder displays its files/folders in the right pane
  • Double clicking on a right pane file “opens” that file
  • For an executable file (.exe) this will run the program in that file
  • For data files the program designated for that file extension opens to show the data
  • Allows files to be created, copied, moved, deleted, renamed, andcompressed
  • Know how to used the “drag and drop” method to move or copy files
  • Select many consecutive files - hold down shift key and click the first and last
  • Select many random files - hold down ctrl key and click on each file

Unit 1C – Computer Networks

Computer network - connects at least two but usually many more computers together

Purpose of a computer network is to allow sharing of data and devices (aka resources)

Local Area Network (LAN) – a computer network in a limited geographic area

Wide Area Network (WAN) – a computer network covering a broad geographic area

  • The Internet is the classic example of a WAN
  • A WAN is made up of a network of LANs

Wired LAN connectivity

  • Uses Ethernet technology to manage devices on the LAN
  • Must have a network interface card that provides an RJ45 port

Wireless LAN connectivity

  • Referred to as WiFi
  • Requires a wireless card for the client computer (now standard on laptops)
  • Requires a wireless router to broadcast the wireless signal

Server – a computer that provides data to other computers on a network

Client – any computer that requests and receives data from a server

The client/server model is very common in today’s networks

Unit 1D – Digital Data

Digital – the use of discrete values to represent information

  • A light switch can be on or off
  • A staircase allows you to be a given set of distances above the floor

Analog – the use of a continuous stream of values to represent information

  • A dimmer allows for all possible levels of brightness in the operating range
  • A ramp allows you to be any possible distance above the floor

Historically, nearly all devices were analog

Many devices already have or are moving from analog to digital

  • Cell phones have already transitioned from analog to digital
  • Records and cassette tapes have transitioned to CDs
  • Videocassettes have transitioned to DVDs
  • Televisions are currently in transition from analog to digital (HDTV is digital)

Computers use digital format to represent data – all data is a series of 1’s and 0’s

Each 1 or 0 is called a bit… a contraction of the term binary digit

Eight bits are required to represent a single character, referred to as a byte

A bit is represented by a lower case “b”… A byte is represented by an upper case “B”

A data representation scheme to represent numbers, letters, and special characters

Personal computers today use a data representation scheme called extended ASCII

The original ASCII data representation scheme used 7 bits to represent 128 characters

The extended ASCII scheme uses 8 bits to represent 256 different characters

Computers use the binary (or base 2) system to represent numbers

Computers use powers of 2 when representing data and reporting storage size

  • The prefix kilo actually means 210 power or 1,024
  • The prefix mega actually means 220 power or 1024 x 1024
  • The prefix giga actually means 230 power or 1024 x 1024 x 1024

Pictures are represented with nothing but 1s and 0s by:

  • Breaking the picture down into a large number of discrete points called pixels
  • Determining one specific color for each point
  • Saving the following information:
  • color for each point (1 byte)
  • row position of each point (1 byte)
  • column position of each point (1 byte)
  • Thus each pixel requires 3 bytes and there are thousands of pixels in an image
  • An image requires a great deal of storage while a paragraph requires little