NIT Excellent Engineer Program. Thanks for Thomas.

Info:

Book Name: Computer Science Made Simple (by V.ANTON SPRAUL) Teacher: Thomas Wong(from NYIST) Powered By: Vitas

Reference: Wikipedia(Only use English version)

Chapter 2

Info:

Updated: 10/16/2015 Total Words: About 2243

Summary:

The title of this chapter is Basic Computer Concepts, so we can get the main idea from it. It’s about some terms and concepts of computer that we must know about, because these are most fundamental knowledge of the device we use a lot in our modern life.

The key terms will be set as italic type, and they will be bold so we can find them easily.

Some description of the term from the book, other from my own words or Wikipedia.

Key Terminology and Concepts

Classification of Computers

From this subtitle, we could know about the main content of this section. It’s about the different kinds of computers we have seen or not.

Basic terms

computer

Definition: A computer is a general-purpose device that can be programmed to carry out a set of arithmetic or logical operations automatically.

Before we learn the terms of computer, we should know what is a computer. The computers have been used everywhere, we could’s live without them. They stand for the high-technology. They make our life colorful and easy.

device

Definition: A tool we use to produce something.

In computer science, we consider any parts of hardware components are all devices.

terminal

Definition: A kind of equipment in computer field, that usually consisting of a keyboard (input device) and a screen (output device) that joins the user to a central computer system (like mainframe).

But if a terminal is nothing more than a screen and keyboard, it’s called dumb terminal.

Key Terms

personal computer

Definition: A general-purpose computer whose size, capabilities and original sale price make it useful for individuals, and is intended to be operated directly by an end-user with no intervening computer operator.

A personal computer could only be used by one person at one time. It’s the difference from some other kinds of computer (like mainframe, minicomputer). The related term PC is usually means the Wintel platform now.

laptop

Definition: A portable personal computer with all the devices inside a single so that is suitable for mobile use.

Laptop is a kind of personal computer, but it’s light and small because it contains all the devices inside a single, so it’s easy to carry everywhere in our daily life. This term is same to notebook.

workstation

Definition: A set of computers that connected together to share data with the network.

The company often use the workstation, because it’s convenient to share the customers’ data with the Local Area Network.

mainframe

Definition: A powerful computer that is shared by multiple users, each user has a terminal that could work separately.

Mainframes often used primarily by large organizations for critical applications, bulk data processing such as census, industry and consumer statistics, enterprise resource planning and transaction processing.

minicomputer

Definition: A smaller computer that is used by multiple users, but its price and capabilty is lower than a mainframe.

Minicomputers are developed in the mid-1960s, they are becoming history.

supercomputer

Definition: A computer with a high-level computational capacity compared to a general-purpose computer.

China does well in this field, we have Tianhe-1A, Tianhe-2 that are famous around the world for the fastest computational capability.

server

Definition: A kind of computer that is on a network to provide a service to other computer which is in its LAN.

A mainframe, even a personal computer is enough powerful to be a server. A server often provide network or data service for the other computer.

client

Definition: A computer that uses a server for some remote service.

A client could send requirements to the remote service, so we don’t need set the client and server nearly. It could work by the special network or telephone lines.

Binary

Numeral system has different kinds. Such as decimal system, binary system, octal system, hexadecimal system and so on. Each of them has different uses.

Binary Basics

binary

Definition: A kind of numeral system that is often used in information technology.

Binary means has two states. One is off, the other one is on. Any data can be stored as binary (numeric data and textual data).

off

Definition: 0(in binary)

on

Definition: 1(in binary)

Binary in Computer Science

bit

Definition: A bit is the basic unit of information in computing and digital communications.

It’s come from the term binary digit.

byte

Definition: The byte is a unit of digital information that most commonly consists of eight bits.

character

Definition: A character is a unit of information that is any letter, digit or other symble that can displayed by typing on a keyboard.

Different programming languages have different sizes of character. In Java, one character is equal to 16 bits or 2 bytes. But in C/C++, one character is equal to 8 bits or 1 bytes.

Digtal Versus Analog

discrete data

Definition: Discrete data are produced when a variable can take only distinct fixed values.

analog data

Definition: Analog data are produced when a variable can be take any continuous value between two values.

digital

Definition: Digital is a binary form which discrete data stored in.

The analog data first has to be turned into discrete data, then a binary encoding couble be assigned to each values.

quantization

Definition: Definition means the process of converting an analog data to the data with ditinct values.

This process isn’t perfect, it may lose some of the original data.

quantization error

Definition: Quantization error is the difference between analog data and its discrete representation.

It could be reduced by having more possible digital values.

sampling

Definition: Sampling means taking analog measurements at intervals and then quantizing each measurements.

We often use this term in music field. The audio is sampled many times per second. (Capture the entire original signal, then turn into numbers.)

sample rate

Definition: Sample rate is the number of samples taken per second.

bits per sample

Definition: Bits per sample means how large a range is given to each quantized value.

Power of 2

A power of two means a number of the form 2^n where n is an integer in computer science. So computers are described as a number like 256, or 512.

Size Terminology

General value:

1 gigahertz = 1,000 megabits = 1,000,000 kilobytes

Computer science value:

1 G = 1,024 M = 1,048,576 k

System Components

The system components is the different devices that make a computer useable. In this section, we could learn the different devices of a computer.

case

Definition: A case is the box that contains the circuitry of the actual computer, along with some devices and connections for others.

tower

Definition: A tower is the case that is taller than it’s wide and sits on the floor.

input device

input device

Definition: An input device is a device that is used to providing data or sending signal to the computer system.

keyboard

Definition: A keyboard is a device like a typewriter, so we can use it input words or some functions.

keypad

Definition: A keypad is an area of a keyboard on the right has numeric keys.

mouse

Definition: A mouse is a device that moves a cursor to click on something in the screen.

mouse pad

Definition: A piece of mouse pad is a pad that designed for moving mice easily.

optical mouse

Definition: An optical mouse is a improved design of mice that use optical sensor to move cursor.

scanner

Definition: A scanner is a device that could convert printed images into computer images.

The scanners are useless now, we all have phones. It’s easy to catch graphics.

digital camera

Definition: A digital camera is a device that uses optical sensors to capture a photo directly.

The digital camera is out-fashion, because the phones also have camera sensor, and they’re easier to carry.

gamepad

Definition: A gamepad is a device that is often used to play games.

The gamepads also sold with the famous game boxs, like XBox One, PS4, Wii and so on.

output device

output device

Definition: An output device is a device that convert the electronically information into the form we can read.

monitor

Definition: A monitor is a computer display screen to display information for the user.

CRT

Definition: A CRT(cathode ray tube) is a device that produces a stream of electrons like televisions to display.

The size of CRT is too large, it’s defficult to carry.

LCD

Definition: A LCD(liquid crystal display) is a device that uses the properties of liquid crystals to light and display.

The size of LCD is much smaller than CRT.

printer

Definition: A printer is a device we use to convert documents into printed files.

dot-matrix printer

Definition: A dot-matrix printer is a kind of printer that works by pressing an inked ribbon against the paper with a set of pins.

Price: Inexpensive Rate: Very fast Quality: Poor

ink-jel printer

Definition: A ink-jel printer is a kind of printer that works by spraying ink at the paper.

Price: Inexpensive Rate: Much slower than a dot-matrix printer Quality: Better-looking image Use: They are default printers for home users and for business users who only print occasionally.

laser printer

Definition: A laser printer is a kind of printer that works by using electrostatic principles to transfer ink to the paper.

Price: They are more expensive than ink-jet printers for an initial purchase, but the cost of ink can be less Rate: Fast Quality: Excellent Use: They are often used for business communications, where print quality counts, although prices have gone down enough that home users who want higher quality purchase them also.

toner

Definition: The toner is a powder form of ink that has been given the opposite charge of the drum.

fuser

Definition: The fuser is a set of very hot rollers that melt the toner into the paper.

The laser printer sometimes may wait for the fuser to reach the right temperature.

dye sublimation printer

Definition: The dye sublimation printer is a kind of printer that works by heating a ribbon so that the solid ink inside turns into a gas and then seeps into the paper.

Price: Very expensive Rate: Not Mentioned Quality: High-quality Use: They are only needed for professional quality photographic printing.

speaker

Definition: The speaker is a device that helps computer output sound.

The speakers also have different styles, like sound boxes, headphones and so on. The speakers could notice us, help us enjoy music or enhance the game’s reality.

Storage Devices

file

Definition: The file is a collection for storing information.

storage device

Definition: The storage device is a device that store files and allow writing and reading the data of files.

tape drive

Definition: The tape drive is kind of device that records information on tape.

The tape drive is a sequential access device. It’s not convenience to jump if the users want to see a significative scene of video.

(read/write) heads

Definition: The (read/write) heads refer to the small electromagnets that produce or retrieve signals from magnetic media.

sequential access device

Definition: The sequential access device means the device must be processed in order.

random access device

Definition: The random access device means the users could jump to any point without going through the previous points first.

backup

Definition: The backup is a copy of all the data on a computer’s primary storage device to prevent data lost.

The tape drive are cheap to back up our important data.

floppy drive

Definition: A floppy drive is a flexible circle of plastic that stores data magnetically.

The floppy drive only could store 2~3 M data. It stores too less than DVD or other storage device now.

removable media

Definition: The removable media is a device that could be easily taken out of the computer and taken elsewhere.

The floppy drive is an example of removable media. (Now we have USB flash disk.)

hard drive

Definition: The hard drive stores data on a rigid magnetized disk or set of disks.

The hard drive could store much more than others. A hard drive can store 500 G, 1 T or more. And it’s much faster at writing and retrieving data.

seek time

Definition: The seek time is the length of time needed to move the heads over a specified track.

The seek time shows the performance of hard drives. Current hard drives have seek times under 10 milliseconds.

fragmentation

Definition: The fragmentation is the state where files have been split up into small pieces across the disk.

defragmenter

Definition: The defragmenter is a program shuffles the files fragments around to get them all contiguous again, improving performance.

optional drive

Definition: The optical drive reads data using a laser and light sensor.

The laser light reflects differently off the bumps and smooth parts of the disc to produce the binary 1 and 0 signals.

CD-ROM(read-only memory) drive

Definition: The CD-ROM(read-only memory) drive is a CD reader that stores data that can be read but not altered.

read-only memory

Definition: The read-only memory is a kind of sstorage media that can be read but not writen.

CD-RW drive

Definition: The CD-RW drive is a read/write drive.

burning

Definition: The burning means to create a CD.

DVD drive

Definition: The DVD drive is a device in a computer system for reading DVDs.

disk/disc

Optical media: disc eg. CD, DVD

Magnetic media: dick eg. floppy drive, hard drive