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What is a computer?
What is a computer?
A computer is an electronic device that executes the instructions in a program. A computer has four functions:
Input
Input
a. accepts data
Processing
Processing
b. processes data
Output
Output
c. produces output
Storage
Storage
d. stores results
Some Basic Terms
Some Basic Terms
Hardware
the physical parts of the computer.
Software
the programs (instructions) that tell the computer what to do
Data
individual facts like first name, price, quantity ordered
Information
data which has been massaged into a useful form, like a complete mailing address
What makes a computer powerful?
What makes a computer powerful?
Speed
A computer can do billions of actions per second.
Reliability
Failures are usually due to human error, one way or another. (Blush for us all!)
Storage
A computer can keep huge amounts of data.
Personal or micro
Personal or micro
Computers for personal use come in all shapes and sizes, from tiny PDAs (personal digital assistant) to hefty PC (personal computer) towers. More specialized models are announced each week - trip planners, expense account pads, language translators...
Hand-held (HPC)
PDA
Tablet PC
Laptop
Desktop
Tower
Workstation
Main frame
Main frame
The main frame is the workhorse of the business world. A main frame is the heart of a network of computers or terminals which allows hundreds of people to work at the same time on the same data. It requires a special environment - cold and dry.
Supercomputers
Supercomputers
The supercomputer is the top of the heap in power and expense. These are used for jobs that take massive amounts of calculating, like weather forecasting, engineering design and testing, serious decryption, economic forecasting, etc.
Other Important Terms
Other Important Terms
Server
Server
The term server actually refers to a computer's function rather than to a specific kind of computer. A server runs a network of computers. It handles the sharing of equipment like printers and the communication between computers on the network. For such tasks a computer would need to be somewhat more capable than a desktop computer. It would need:
more power
larger memory
larger storage capacity
high speed communications
What is Input?
What is Input?
Input
Input
Processing
Processing
Output
Output
Storage
Storage
Everything we tell the computer is Input.
Everything we tell the computer is Input.
Types of Input
Types of Input
Data is the raw facts given to the computer.
Programs are the sets of instructions that direct the computer.
Commands are special codes or key words that the user inputs to perform a task, like RUN "ACCOUNTS". These can be selected from a menu of commands like "Open" on the File menu. They may also be chosen by clicking on a command button.
User response is the user's answer to the computer's question, such as choosing OK, YES, or NO or by typing in text, for example the name of a file.
Keyboard
Keyboard
The first input device we will look at is the Keyboard. The image used on the next page to illustrate the various keys may not look like the keyboard you are using. Several variations are popular and special designs are used in some companies. The keyboards shown below put the function keys in different places. The Enter and Backspace keys are different shapes and sizes. One has arrow keys while the other doesn't. It's enough to confuse a person's fingers!!
The backslash key has at least 3 popular placements: at the end of the numbers row, above the Enter key, and beside the Enter key. We also have the new Windows keyboards which have two new keys. One pops up the Start Menu and the other displays the right-click context sensitive menu. Ergonomic keyboards even have a different shape, curved to fit the natural fall of the wrists.
POINTING DEVICES
POINTING DEVICES
A variety of pointing devices are used to move the cursor on the screen.
The most commonly used ones have two or three buttons to click and for special functions.
Mouse
A ball underneath rolls as the mouse moves across the mouse pad. The cursor on the screen follows the motion of the mouse. Buttons on the mouse can be clicked or double-clicked to perform tasks, like to select an icon on the screen or to open the selected document.
There are new mice that don't have a ball. They use a laser to sense the motion of the mouse instead. High tech!
Advantage:
Moves cursor around the screen faster than using keystrokes.
Disadvantage:
Requires moving hand from keyboard to mouse and back.
Repeated motion can lead to carpal tunnel syndrome
Trackball
Instead of moving the whole mouse around, the user rolls the trackball only, which is on the top or side.
Advantage:
Does not need as much desk space as a mouse.
Is not as tiring since less motion is needed.
Disadvantage:
Requires fine control of the ball with just one finger or thumb.
Repeated motions of the same muscles is tiring and can cause carpal tunnel syndrome.
Glidepad
Uses a touch sensitive pad for controlling cursor. The user slides finger across the pad and the cursor follows the finger movement. For clicking there are buttons, or you can tap on the pad with a finger. The glidepad is a popular alternate pointing device for laptops.
Advantage:
Does not need as much desk space as a mouse.
Can readily be built into the keyboard.
Has finer resolution. That is, to achieve the same cursor movement onscreen takes less movement of the finger on the glidepad than it does mouse movement.
Can use either buttons or taps of the pad for clicking.
Disadvantage:
The hand tires faster than with a mouse since there is no support.
Some people don't find the motion as natural as a mouse.
Game Devices
Cursor motion controlled by vertical stick (joystick) or arrow buttons (gamepad)
Advantage:
A joystick gives a more natural-feeling control for motion in games, especially those where you are flying a plane or spaceship.
Both have more buttons for special functions than a mouse and can combine buttons for even more actions.
Disadvantage:
More expensive
Bulky
Better ones require an additional peripheral card for best performance
Pen Input
Used esp. in Personal Digital Assistants (PDA)
Pen Input is used for:
Data Input -
by writing. PDA recognizes your handwriting. (If only your friends could, too!)
Pointing Device -
Functions like a mouse in moving a cursor around the screen and clicking by tapping the screen.
Command Gestures -
You can issue commands by moving pen in patterns. So a certain kind of swirl would mean to save the file and a different kind of swirl could mean to open a new file.
Advantage:
Can use handwriting instead of typing
Can use gestures instead of typing commands
small size
Disadvantage:
Must train device to recognize handwriting.
Must learn gestures or train device to recognize the ones you create
Can lose the pen which is not usually attached to the device
Touchscreen
Make selection by just touching the screen.
Advantage:
It's natural to do - reach out and touch something.
Disadvantage:
It's tiring if many choices must be made.
It takes a lot of screen space for each choice since fingers are bigger than cursors.
Digitizers and Graphics Tablets
Converts drawings, photos, etc. to digital signal.
The tablets have special commands
What is Output?
What is Output?
Input
Input
Processing
Processing
Output
Output
Storage
Storage
Output is data that has been processed into useful form, now called Information
Types of Output
Types of Output
Hard copy:
printed on paper or other permanent media
Soft copy:
displayed on screen or by other non-permanent means
Categories of Output
Categories of Output
Text documents including reports, letters, etc.
Graphics
charts, graphs, pictures
Multimedia
combination of text, graphics, video, audio
PRINTER
PRINTER
The job of a printer is to put on paper what you see on your monitor. How easy this is to do and how successfully it is done determines whether or not you are happy with your printer choice.
Monitor screens and printers do not use the same formatting rules. In the olden days of computers, the way something looked on the screen could be VERY different from how it would look when printed.
Early word processors didn't have a way to show what the printed version would look like. Now a word processor that doesn't have print preview, would be laughed off the shelf. Most have a WYSIWYG view, where you see almost exactly what the document will look like in print, while you are still working on it.
Operating systems
Operating systems
Between the hardware and the application software lies the operating system. The operating system is a program that conducts the communication between the various pieces of hardware like the video card, sound card, printer, the motherboard and the applications.
Operating systems
Operating systems
Between the hardware and the application software lies the operating system. The operating system is a program that conducts the communication between the various pieces of hardware like the video card, sound card, printer, the motherboard and the applications.
Between the hardware and the application software lies the operating system. The operating system is a program that conducts the communication between the various pieces of hardware like the video card, sound card, printer, the motherboard and the applications.
Application Programs
Application Programs
Application programs are meant to accomplish specialized tasks they are designed for.
Word Processing
Word Processing
There are many different kinds of applications, all with lots of spiffy features. Word processing is the application that is used most often and most widely. We will start with it to learn about the terms and features that are common to most applications, as well as some that are specific to word processing. Then we will look at other major applications and what they do.
Major word processors include Microsoft Word, WordPerfect, and Lotus WordPro.
Spreadsheet
Spreadsheet
A spreadsheet is the application of choice for most documents that organize numbers, like budgets, financial statements, grade sheets, and sales records. A spreadsheet can perform simple or complex calculations on the numbers you enter in rows and columns.
Some popular spreadsheets include MS Excel, Lotus 1-2-3, and Quattro Pro.
Purpose:
Organizing numbers
Organizing numbers
Major Advantages:
Major Advantages:
Can calculate for you using formulas
Can calculate for you using formulas
Auto-update of related numbers when data changes
Auto-update of related numbers when data changes
Can display data in graphs and charts
Can display data in graphs and charts
Database
Database
A database is a collection of data that you want to manage, rearrange, and add to later. It is a good program to use to manage lists that are not entirely numbers, such as addresses and phone numbers, inventories, and membership rosters. With a database you could sort the data by name or city or postal code or by any individual item of information recorded. You can create forms to enter or update or just display the data. You can create reports that show just the data you are interested in, like members who owe dues.
Both spreadsheets and databases can be used to handle much the same information, but each is optimized to handle a different type most efficiently. The larger the number of records, the more important the differences are.
Some popular databases include MS Access, dBase, FoxPro, Paradox, Approach, and Oracle.
Purpose:
Managing data
Managing data
Major Advantages:
Major Advantages:
Can change way data is sorted and displayed.
Can change way data is sorted and displayed.
Graphics
Graphics
Graphics programs deal with pictures, either static or moving, flat or 3D. There are an amazing number of different formats for images in the world and no one program can handle them all.
Adobe Photoshop is the most widely used graphics program for professionals. PaintShopPro is popular because it offers most of Photoshop's features at a lower cost and with a friendlier interface. There are many other programs. Some specialize in handling photographs or animations or creating logos.
Purpose: To create and edit images
Presentations
Presentations
This kind of program links together a sequence of slides containing text and graphics, for example for a sales presentation or training. It includes a number of tools for creating graphics that are quite useful.
Examples of presentations programs: Microsoft PowerPoint, Corel Presentations, Lotus Freelance Graphics
Purpose:
Turning information into visual form
Turning information into visual form
Major Advantage:
Major Advantage:
Pictures convey info faster than tables of numbers.
Pictures convey info faster than tables of numbers.
Communications
Communications
These programs temporarily connect computers to each other to exchange information. They may use telephone lines or dedicated cables for the connection. This allows you, for example, to work at home on the weekend and transfer all you've done to your computer at work before you leave home.
These are not the same as networking programs where computers are actually linked together all the time.
Most communications programs now include many different communication functions in one interface.
Purpose:
Transmitting data and messages between computers
Major Advantage:
Speed
A communications program includes one or more of the following actions:
sending and receiving files: FTP (File Transfer Protocol)
exchanging messages in a group: chat programs
private messages: instant messaging
voice messages
video conferencing
phone calls over the Internet
Browser
Browser
An Internet browser is a program that lets you navigate the World Wide Web. [It's what you are using to view this page!]
A browser displays web pages, keeps track of where you've been, and remembers the places you want to return to.
More information is available over the Internet every day, and more tasks can be done. You can buy books, check on your bank account, buy and sell stocks, even order pizza over the Internet. But you have to have a browser to do it.
Internet Explorer is by far the most popular browser, though there are many others around. Netscape was once the dominant browser and is still used, but it is falling further behind in market share all the time.
Purpose:
Navigating the Internet
Major Advantage:
Can display graphics, which older internet applications don't
Keeps a list of places you want to return to.
Email
Email
Email, or electronic mail, is becoming more and more popular as people learn to communicate again with written words. For many purposes it is superior to a phone call because you don't have to catch the person in and you can get straight to the point. No time is wasted on casual conversation. It also leaves a written record to refer back to for a response or if you forget who said what. Email is superior to the traditional office memo because it uses no paper (Save the trees!!) and it can be sent to a whole list of people instantly.
Commonly used email programs include Microsoft Outlook Express, Microsoft Outlook, Netscape Mail, Eudora, and Pegasus.
Purpose:
Transmitting messages between computer users
Major Advantage:
Speed
Major Disadvantage:
You don't know if the receiver actually reads it, though you can find out if they received it. Of course in a phone conversation you don't really know if the person is actually listening either!
With no body language or vocal intonations it is difficult to convey the emotional tone you want. Irony and sarcasm are particularly dangerous since your reader may take you seriously.
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