INTRODUCTION
What is a computer?
A computer is an electronic device that executes the instructions in a program.
A computer has four functions:
a. accepts data
Input
The Information Processing Cycle
b. processes data
Processing
c. produces output
Output
d. stores results
Storage
In the lessons that follow we will study the parts of the computer and each of the four parts of the Information Processing Cycle.
Some Beginning 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
Default
the original settings; what will happen if you don't change anything.
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.
Types of Input
Data means 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
· MOUSE
, PROCESSING
Processing is the thinking that the computer does - the calculations,
comparisons, and decisions. People also process data. What you see and hear and touch and feel is input. Then you connect this new input with what you already know, look for how it all fits together, and come up with a reaction, your output. "That stove is hot. I'll move my hand now!"
The kind of "thinking" that computers do is very different from what people do.
Machines have to think the hard way. They do one thing at a time, one step at a time. Complex procedures must be broken down into VERY simple steps. Then these steps can be repeated hundreds or thousands or millions of times. All possible choices can be tried and a list kept of what worked and what didn't.
People, on the other hand, are better at recognizing patterns than they are at single facts and step-by-step procedures. For example, faces are very complex structures. But you can identify hundreds and even thousands of different faces.
A human can easily tell one face from another, even when the faces belong to strangers. You don't recognize Mom's face because you remember that Mom's nose is 4 cm long, 2.5 cm wide, and has a freckle on the left side! You recognize the whole pattern of Mom's face. There are probably a lot of folks with noses the size and shape of Mom's. But no one has her whole face.
But a computer must have a lot of specific facts about a face to recognize it. Teaching computers to pick Mom's face out of a crowd is one of the hardest things scientists have tried to do yet with computers. But babies do it naturally!
So computers can't think in the same way that people do. But what they do, they do excellently well and very, very fast.
MOUSE
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
Text documents including reports, letters, etc.
Graphicscharts, graphs, pictures
Multimediacombination of text, graphics, video, audio
Computer to Computer: Intro
Computer communication is the transmission of data and information over a communications channel between two computers, which can be several different things.
Communications between computers can be as simple as cabling two computers to the same printer. It can be as complex as a computer at NASA sending messages through an elaborate system of relays and satellites to tell a computer on Mars how to drive around without hitting the rocks.
Depending on the context, for computer communications you might use the terms:
Data Communications for transmission of data and information over a communications channel Telecommunications for any long-distance communications, especially television Teleprocessing for accessing computer files located elsewhere
Communications Channel
A communications channel, also called a communications line or link, is the path that the data follows as it is transmitted from one computer to another.
Below is an animation of a communications channel at work. A PC is sending a message to a host computer clear across the country. Notice the variety of transmission methods used: telephone lines, satellite links, microwave relay. This is a simplified version of what really goes on! (The animation runs 10 times and stops. To restart it, use your browser's Refresh command.)
WE KNOW VINO
