Bài giảng tiếng anh chuyên ngành it01 Đại học mở hà nội

Nội dung 1.1 Definition of Computer A computer may be defined as an electronic machine, which accepts data from an input device and processes it by performing arithmetical and logical operations in accordance with a program of instructions and returns the results through an output unit 1.2 Computer Types In the 1970s and 1980s a new type of computer started to gain in popularity. It was called the PC or personal computer. For the first time in history, computers were now for everyone. The PC started a revolution which affects nearly everything we do today. The ways we work, play, communicate, and access information have all been radically reshaped due to the invention and evolution of the PC. PCs are everywhere you look today. At home, at the office, and everywhere in between. Many people still mistakenly believe the term PC is synonymous with a desktop computer running Windows.

UNIT 1 INTRODUCTION TO THE COMPUTERS

Nội dung

1.1 Definition of Computer

A computer may be defined as an electronic machine, which accepts data from

an input device and processes it by performing arithmetical and logical operations in accordance with a program of instructions and returns the results through an output unit

1.2 Computer Types

In the 1970s and 1980s a new type of computer started to gain in popularity It was called the PC or personal computer For the first time in history, computers were now for everyone The PC started a revolution which affects nearly everything we do today The ways we work, play, communicate, and access information have all been radically reshaped due to the invention and evolution of the PC

PCs are everywhere you look today At home, at the office, and everywhere in between Many people still mistakenly believe the term PC is synonymous with a desktop computer running Windows This is not really true Really, any computer

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you use by yourself for general purposes could be called a PC You probably already own at least one of these types of PCs:

Embedded systems can be found in traffic lights, TV sets, refrigerators, coffee machines and many more devices Embedded systems are typically controlled by inexpensive, specialized processors which can only handle very specific tasks

Types of computers go in and out of fashion as times changes Older kinds of computers which were very popular in the 20th century (1900's) are now referred to as legacy systems These include:

- Mainframes

- Minicomputers

- IBM clones

Mainframe Minicomputer IBM clone

New types of computers are always coming out and replacing or augmenting

existing computer types Examples of new types of computers emerging would be

netbooks, tablet PCs, and even wearable computers

As you complete this unit, you will learn to differentiate between different

computer types Keep in mind that the lines between computer types are constantly

being blurred This phenomenon is known as convergence

1.3 Part of an Information System

The way to think about a microcomputer is a part of an information system and

not only as an equipment An information system has five parts:

-People:

They comprise mostly of end users These are people who use microcomputers

to meet their needs for information

-Procedures:

These are rules or guidelines for people to follow when using software,

hardware, and data Typically, these procedures are documented in manuals written by

specialists for particular organizations

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-Software:

It is another name for a program A program is step –by-step instructions that tell the computer how to do its work The purpose of software is to convert data, that is, unprocessed facts into information (processed facts) As such there are 2 types of software: Application software and System software

Application software may be described as end-user software, System software enables the application software to interact with the computer, System software is referred to as background software

-Hardware:

The hardware consists of the physical equipment: keyboard, monitor, system unit and other devices Hardware is controlled by software It actually processes the data to create information It falls into 5 categories: -input devices, system unit, secondary storage, output devices and communication devices Other extra parts called peripheral components or devices include mouse, printers, modems, scanners, cards (sound, color, and video) and so

on

Thus hardware is divided into four basic categories:

+input: keyboard and other devices

+processing: microprocessor chips and memory

+storage: floppy and hard disk drives

+output: displays, monitors, printers and chips

-Data:

Data consists of the raw, unprocessed facts Examples of raw facts are hours worked After data is processed through the computer it is called information An example of such information is the total wages for a week’s work

Useful Vocabulary:

1 Convergence

The evolution of devices towards common functionality

The iPhone is a good example of convergence It has all the features of a

PDA, mobile phone, and an MP3 player in one package

2 Embedded system

A computer using a relatively slow and specialized processor and ROM chip,

normally used to control a particular device such as a washing machine or an MP3

An older computer system that continues to be used because an organization

does not wish to redesign it with a more modern device

Mainframes and minicomputers used to be cutting edge; now they are known

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card in my netbook could only handle Solitaire

6 PC ( personal computer)

A computer designed for use by one person at a time

When people use the term 'PC', they are often referring to a desktop computer running Windows

7 PDA(personal digital assistant)

A handheld computer about the size of wallet used as an

organizer, web browser, game machine, mobile phone, or message

recorder; also known as a hand-held computer

The modern traveling businessman depends on his PDA to organize all his contacts and appointments

8 print server

A physical or software device connecting and facilitating a network with a printer

The secretary could not get a hard copy because the print server was broken

9 router

A specialized computer which connects two networks

The DSL router allowed the entire office to share a single Internet connection

Refers to only the most powerful class of computer, typically designed to

perform specialized tasks such as weather prediction, governmental financial

calculations, or space research

A typical supercomputer may have up to 100 processors and have speeds

measured in tens of gigaflops

12 tablet PC

A portable computer shaped in the form of a notebook and capable of

advanced handwriting recognition via the use of a stylus or on-screen keyboard

Bill Gates predicted the rise of the tablet PC in 2001, but not much happened

until Apple announced the iPad in 2010

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UNIT 2 THE CENTRAL PROCESSING UNIT

(CPU)

The computer is composed of the following functional parts: the central

processing unit (CPU), the memory, and one or more input-output (I/O) units

Nội dung

2.1 What is a Central Processing Unit?

In order to work, a computer needs some sort of “brain” or “calculator” The Central Processing Unit (CPU) is the “brain” of the computer; it reads and executes program instructions, performs calculations, and makes decisions The CPU is responsible for storing and retrieving information on disks and other media It also handles information on from one part of the computer to another like a central switching station that directs the flow or traffic throughout the computer system The central processing unit is the essential component of a computer because it is the part that executes the programs and controls the operation of all the hardware Powerful computers may have several processors handling different tasks, although there will

need to be one central processing unit controlling the flow of instructions and data through the subsidiary processors

The CPU resides inside a box, known as the system unit, along with various support devices and tools for storing information

2.2 Main Components and Structure of the CPU

What does the CPU do?

It carries out instructions and tells the rest of the computer system what to do This is done by the Control Unit of the CPU, which sends command signals to the other components of the system

It performs arithmetic calculations and data manipulations, e.g comparisons, sorting, combining, etc The computer’s calculator is a part of the CPU known as the Arithmetic Logic Unit

It holds data and instructions, which are in current use These are kept in the Main Store or Memory

To understand how the whole system

works, consider the diagram shown in Figure

2.2 An actual CPU may have these components

or other with different names that provide the

same function

Control Unit

The control unit of the CPU contains circuitry that uses electrical signals to direct the entire computer system to carry out, or execute, stored program instructions Like an orchestra leader, the control unit does not execute program instructions; rather, it directs other parts of the system to do so It is the “brain within the brain”, as it controls what

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happens inside the processor, which in turn controls the rest of the PC The control unit must communicate with both the arithmetic/logic unit and memory The functions performed by the control unit vary greatly by the internal architecture of the CPU, since the control unit really implements this architecture On a regular processor the control unit performs the tasks of fetching, decoding, managing execution and then storing results The control unit uses the instruction contained in the Instruction Register to decide which circuits need to be activated It co-ordinates the activities of the other two units as well as all peripherals and auxiliary storage devices linked to the computer The control unit instructs the arithmetic logic unit which arithmetic operations or logical operation is to be performed It is literally in contron

Memory Unit

The Memory Unit is the part of the computer that holds data and instructions for processing Although it is closely associated with the CPU, in actual fact it is separate from it Memory associated with the CPU is also called primary storage, primary memory, main storage, internal storage and main memory There are two types of computer memory inside the computer, RAM and ROM

RAM ( Random Access Memory)

This is really the main store and is the place where the programs and software

we load gets stored When the Central Processing Unit runs a program, it fetches the program instructions from the RAM and carries them out If the Central Processing Unit needs to store the results of calculations it can store them in RAM Random Access Memory can have instructions read from it by the CPU and also it can have numbers or other computer data written to it by the CPU The more RAM in your

computer, the larger the programs can run When we switch a computer off, whatever is stored in the RAM gets erased

ROM ( Read Only Memory)

ROM is “built-in” computer memory containing data that normally can only be read, not written to ROM contains the programming that allows your computer to be

“booted up” or regenerated each time you turn it on The data in ROM is not lost when the computer power is turned off The ROM is sustained by a small long-life battery in your computer If you ever do the hardware setup procedure with your computer, you effectively will be writing to ROM

Arithmetic Logic Unit

The arithmetic logic unit executes arithmetic and logical operations Arithmetic operations include addition, subtraction, multiplication and division Logical operations compare numbers, letters and special characters

Comparison operations test for three conditions:

Equal –to condition: ALU compares two values to determine if they are equal For example: If the number of tickets sold equal the number of seats in the auditorium, then the concert is declared sold out

Less-then condition: The computer compares values to determine if one is less than another For example: If the number of speeding tickets on a driver’s record is less than three, the insurance rates are $425; otherwise, the rate are $ 500

Greater- than condition: The computer determines if one value is greater than another For example: If the hours a person worked this week are greater than 40, then multiply every extra hour by 1.5 times the usual hourly wage to compute overtime pay

Relational operations (= <, >) are used to describe the comparison operations used by the arithmetic logic unit

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The arithmetic logic unit performs logic functions such as AND, OR and NOT

The accumulator is used to accumulate results It is the place where the answers from many operations are stored temporarily before being put out to the computer’s memory The other general-purpose registers hold data on which operations are to be performed by the arithmetic logic unit

2.3 How the CPU works

The CPU is centrally located on the mother board Since the CPU carries out a large share of the work in the computer, data pass continually through it The data come from the RAM and the units (keyboard, drives, etc.) After processing, the data

is sent back to the RAM and the units The CPU continually receives instructions to

be executed Each instruction is a data processing order The work itself consists mostly of calculations and data transport

The CPU performs four steps in executing and instruction:

The control unit gets the instruction from memory

The control unit decides what the instruction means and directs the necessary data to be moved from the memory to the arithmetic logic unit

The arithmetic logic unit performs the actual operation on the data

The result of the operation is stored in memory or a register

The first two instructions make up what is called the instruction time The last two instructions make up what is called the execution time The combination of these two is called a machine cycle Each central processing unit has an internal clock (or system clock), which produces pulses at a fixed rate to synchronize all computer operations A single machine cycle instruction is made up of a number of sub-instructions, each of which must take at least one clock cycle Each type of CPU is designed to understand a specific group of instructions called the instruction set

2.4 Definition of a microprocessor

In a microcomputer, the CPU is contained on a single

silicon chip called the microprocessor A microprocessor,

as shown in figure, is a computer processor on a microchip

It’s sometime called a logic chip It is the “engine” that

goes into motion when you turn your computer on A

microprocessor is designed to perform arithmetic and logic

operations that make use of small number-holding areas called registers Typical microprocessor operations include adding, subtracting, comparing two numbers, and fetching numbers from one area to another When the computer is turned on, the microprocessor is designed to get the first instruction from the Basic Input/ Output System (BIOS) that comes with the computer as part of its memory

2.5 Input and Output Devices

2.5.1 Input devices

We use input devices every time we use a computer Simply speaking, it is these devices which allow us to enter information Without them, the computer would not know what we want it to do

Some of the things we do with input devices are: move a cursor around the screen, enter alphanumeric text, draw pictures, and even enter binary data in the form of graphics

or audio wave forms

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Input devices have a history as long as computers themselves Perhaps the first input device was the simple electronic switch (similar to a light switch) which turned bits on or off There were hundreds or even thousands of these switches on larger computers It used to take a team of programmers hours or even days to set up a computer to perform a single calculation

Switches and jumpers are still used today on computers For instance the power button on the computer is a switch which is also an input device telling the computer

to power on or power off Tiny switches called jumpers are also widely used on mother boards to change important settings such as processor clock speed or memory speed

Most likely in front of you right now are two of the most popular input devices: the keyboard and the mouse And instead of a mouse on a laptop computer you normally have a touchpad

As computers evolved throughout the late 20th century, computers became more and more interactive Input devices came and went Some lasted and some did not The light pen and the joystick are almost unknown today, although they were popular before the mouse and the gamepad became well-known Touch screens are already replacing keypads on mobile phones and may come to replace or augment keyboards and mice on PCs and laptops in the near future

Different people prefer different input devices for doing same task For instance, many graphic artists prefer to use a stylus and graphics tablet rather than a mouse It might offer them a greater deal of artistic freedom, or precision while performing their work

Sufferers of carpal tunnel syndrome often prefer a trackball or stylus to a mouse Handicapped computer users have invented a wide array of input devices designed to replace the mouse including devices controlled by foot or even eye movement

Not only PCs and mainframes use input devices Almost all computers feature some kind of input devices Special scanners are used in many stores and warehouses called barcode readers to enter stock and sell items at the cashier These are input devices as well Even microphones can technically be called input devices as a computer can respond to them and interpret them as incoming data

Corporations and especially government institutions are already implementing the second generation of input devices to improve security These include retina scanners and/or fingerprint readers to replace or improve accuracy of username and password authentication You will be seeing more of this kind of biometric authentication in the coming years as a general remedy for weak passwords or leaked passwords

In summary, input devices are how you interact with a computer The computer responds to your input and hopefully does what you need it to do It seems really simple, and that's the way it was meant to be!

Useful Vocabulary:

1 Barcode reader

A hardware peripheral designed to 'scan' products into an inventory tracking system

Harry got into trouble during inventory because he forgot to charge his remote barcode scanner

2 Click

To press and release the primary (left-side) mouse button

The screen prompt read, "Click next to continue."

3 Double-click

To depress and release the left mouse button twice in quick succession

The Macintosh user did not know that in order to open a file in Windows you need

to double-click it

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4 Fingerprint reader

A device which forms a digitized image of a human finger print for the

purpose of biometric authentication

The security firm was so tired of people choosing weak passwords that they

installed fingerprint scanners to increase the security of their systems

A peripheral used primarily to enter data into a computer

The mouse and the keyboard are two examples of common input devices

7 Joystick

An input device with a vertical rod mounted on a base used to control

pointing devices or on-screen objects; normally with one or more buttons

The user used a joystick to control the airplane in the flight simulation

8 Light pen

An input device using a light-sensitive pen shaped handle which can be used

to draw on the computer screen

Many older computers used light pens to increase interactivity before the

mouse became a standard

A special icon (normally an arrow) that indicates the current location of the mouse

on the desktop screen

The mouse pointer changes shapes at times depending on the application being run and task being executed or performed

12 OCR (optical character recognition)

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The ability of a computer to determine standard letters and numbers based on

fuzzy logic

Instead of retyping the stack of documents, the secretary decided to OCR

them to save time

13 Right-click

To press the right-side mouse button

Windows 95 was the first major operating system to popularize the

right-click

14 Speech recognition

The ability of a computer to convert spoken words from a user into usable

data

The new phone system used speech recognition to help reduce the number of

customer service representatives

An input device consisting of a sensitive rectangular area in which one uses a

finger to move a cursor on a display

Laptops commonly include a built-in touchpad in addition to supporting a

mouse

17 Touch screen

A display that also acts as an input device by allowing a user to navigate a program

by touching specific locations of the screen

Most information kiosks in airports make use of touchscreens instead of keyboards

2.5.2 The keyboard entry

The keyboard is the most common input device found on computers today You should be familiar with all the keys in order to have a successful career in Information Technology

Here are some common keys you should be familiar with in order to complete this unit:

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The alternate key

The control key

The tab key

The escape key

The function key

The arrow keys

The page down key

The page up key

The delete key

The print screen key

The caps lock key

The hash key

The carpet key

The tilde key

The scroll lock key

Please note: in the USA the ‘hash key’ is most often called the ‘pound sign’

This is very confusing because if you say 'pound key' to a British English speaker he

will probably assume you are referring to the British pound currency symbol ( £ )

A specific key on a computer keyboard that when pressed in conjunction with other keys produces a wider range of characters

Pressing the alt key with another letter key can often result in a program shortcut

2 Arrow keys

A set of four input buttons on a keypad or keyboard often used for navigation in interfaces or applications

The girl used the arrow keys to move the space ship in the video game

3 Caps lock key

A key which when pressed will toggle characters in upper or lower case

Users leaving Caps Lock on is a frequent problem when logging into secure systems

A computer key which changes the meaning of another key

A popular shortcut in Microsoft Word is to hit Ctrl-S to save a document

6 Del (delete key)

A key which moves the cursor one space to the right deleting any character which might be there

Jeremy accidentally fell asleep at his computer, his nose hitting the delete key, and his term paper was completely erased

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7 Esc (escape key)

A key normally in the upper left corner of a keyboard labeled with program

specific functions such as backing out of a menu

The student had never used the escape key before he started programming

the Unix shell

8 Function key

Any one of several "F" keys on the keyboard that performs a programmable

input

Most people have function keys on their keyboards, but only advanced users

ever use them for anything

9 # (hash key)

This key is often used to comment out code or signify a number; in the US

this known as a pound sign or a number key

Often you must press the hash key on a telephone when entering information

into a telephone

10 Pgdn (page down key)

A key which jumps the cursor a preset amount of distance towards the

bottom of a document

Because of varying concepts of a 'page', many programs react differently to

the page down key

11 Pgup (page up key)

A key which jumps the cursor a preset amount of distance towards the top of

a document

The teacher told the students to hit the page up key several times to get to the top of the document

12 Pr Scr (print screen key)

A key which normally captures the current screen to the clipboard to be pasted into

an imaging program

Many graphic designers use the print screen key to take screen shots of applications to be used in tutorials or brochures

13 Scroll lock key

A key, normally with a corresponding LED light, which normally has no assigned use in modern computing

The computer operator suddenly realized after 10 years he had never used the Scroll Lock key for anything

14 Tab key

A key that, when pressed, moves the insertion point to the next preset marker

The usability expert showed the office workers how to save time by using tab instead of the mouse

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2.5.3 Output devices

What is a Computer Output Device?

In the world of computers, input/output (I/O) refers to the communication

between a computer and the user Input is the data sent to the system, whereas

output is the data sent by the system to the outside world Computer output devices

are computer hardware equipments, that are used to communicate the results of data

processing carried out by a computer to the user There are a number of devices,

which produce data in different forms, which includes audio, video or hard copy

Output device of computer are types of peripheral hardware connected that is

connected to the computer, either using cables or over a wireless network

Immaterial whether you have desktop computers, laptop computers,

supercomputers, etc., you will require at least one computer output device

Which Devices are Computer Output Devices?

An output given by the computer can be in the form of a display on the screen or a printed document or a song that is played Most of the computer output devices are

common to home as well as office environments At the same time, there are some

devices, which are not as commonly available Having said that, let’s take a look at

computer output devices list

Monitor

A monitor is also called as video display terminal (VDT) The visual display of the processed data, which the users can view is got through the monitor Computer monitors come in a variety

of screen sizes and not to forget visual resolutions There are two types of computer monitors available, namely CRT and flat panel All monitors rely in a video card, which is located on the motherboard to display the information It is the video card, which processes the data into images, which is eventually displayed on the monitor

Printer

The next of the computer output devices is the printer, which is an external hardware device, which takes processed data from the computer to generate a hard copy of the data After the monitors, printers are the most used peripherals on computers and they are commonly used to print text data, images, etc There are three main types of computer printers, namely ink jet, laser printers and dot matrix Each of these printers uses a different technology to print the data

Speaker

A speaker is a hardware device, that is connected to a computer’s sound card, which outputs sound generated by the card Audio data generated by the computer is sent to the audio card, that is located in the expansion slot The card translates the data into audio signals, which are then sent to either the speakers or headphones In the initial phase, computers had on-board speakers, which generated series of different tones and beeps When the popularity of multimedia and computer games grew, higher quality computer

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speakers came into the market These new speakers were known for higher quality sound effects and music

Projector

It is a hardware device, with which an image like a computer screen is projected onto a flat screen Image data is sent to the video card, by the computer which is then translated into a video image and sent to the projector A

projector is often used in meetings or to make presentations,

because they allow for a large image to be shown, with which the

display is available for a large audience

Plotter

Plotters, like printers, create a hard copy rendition of a digitally rendered design The design is sent to a plotter through a graphics card and the image is created using a pen In simple words, plotters basically draw an image using a series

of straight lines This computer output device is used with engineering applications

Discs

There are different types of discs, such as CDs, DVDs and floppy discs, which are output devices, that are also used to store data, hence they are also input devices

at the same time The data is sent to the disc and the data is embedded on the disc,

This is computer output devices information in short All computers might not have all the computer output devices, but it certainly does have one of the visual output devices, namely either a monitor or projector

Chúc Anh/ Chị học tập tốt!

UNIT 3: STORAGE AND MEMORY

Nội dung

3.1 Main Memory

Memory is used to store the information (programs and data) that the computer is currently using It is sometimes called main or primary memory One form of memory is called RAM, which stands for Random Access Memory This means that any location in memory may be accessed in the same amount of time as any other location The address of a memory cell is used when we wish to access that particular memory location This means that we must know the address of a cell in memory before we can access its contents A byte is a small unit of storage, capable of storing unsigned numbers in the range 0 to 255 In order to allow you to store larger quantities in memory, the hardware allows you to treat a number of consecutive cells as a unit For example, by using two consecutive cells, 16 bits are available for storing information giving an unsigned number range from 0 to 216-1 (65,535) By using 4 consecutive cells, 32 bits are available, allowing numbers in excess of 1 billion to be manipulated

RAM is a form of short term of volatile memory Information stored in short term storage is lost when the computer is switched off or when power fails There is therefore a requirement for permanent or long term storage which is also referred to

as secondary storage This role is fulfilled by disk and tape storage

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3.2 Types of Main Memory

There are two major forms of RAM called static RAM (SRAM) and dynamic RAM (DRAM)

SRAM is the more expensive of the two as it is more complexly manufactured but it is

considerably faster to access than DRAM DRAM has an access time in the range of

60-100 nanoseconds upwards, while SRAM access times range from 4 or 5 nanoseconds upwards It is not uncommon for a computer system to have a small amount of SRAM and

a large volume of DRAM, making up its total RAM capacity The SRAM is used to construct a cache memory which stores frequently accessed information and so speed up memory access for the system

3.3 Primary Memory

There are other forms of Primary memory such as ROM, PROM, EPROM, EEPROM and flash memory

ROM (Read Only Memory): It is the same as RAM in so far as any location can

be read from at random, but it cannot be written to ROM is pre-programmed by the manufacturer and its contents cannot be changed, hence its name read only This means that ROM is a form of permanent storage However, since the user cannot store information in ROM, its usefulness is restricted ROM is typically used to store programs and data that are required to start up a computer system When a computer is powered on, its RAM will contain no useful information, but the processor is designed to runs programs that it finds in memory One major use of ROM is to store the initial program used by the processor when the machine is started Another use of ROM in personal computers is to store operating systems subprograms for carrying out I/O and other

activities The term firmware is used for combination of ROM and the software stored on

it

PROM stands for programmable ROM, which means that the memory chip

manufacturer provides a form of ROM that can be programmed via the use of a special hardware device This allows computer system designers to place their own

programs on the PROM chip If their programs do not operate correctly, the designer can program another PROM chip, as opposed to getting the memory

manufacturer to do it, as is the case when a designer uses ROM

EPROM is a form of ROM that is erasable which means that the contents of the EPROM chip can be erased in their entirety and the chip can be reprogrammed (a limited number of times) As in the case of PROM, EPROM can only be

programmed and erased (via exposure to ultra violet light) by a special hardware device, outside the computer system

EEPROM is electrically erasable PROM EEPROM can be erased inside

the computer system using an electrical current Its major advantage is that does not have to be removed from the computer system

NVRAM: in recent years work has advanced on such non-volatile RAM (NVRAM) devices Flash memory is one such device This memory can be accessed like RAM (read and written), but is non-volatile i.e it is a form of

permanent storage At the time of writing flash memory is available in the 1 to 6

Mb range One disadvantage of current NVRAM is that they cannot be written to,

as quickly as ordinary RAM However, they are much faster to access than disk

storage systems and they consume less power, so that in small portable computer systems they offer an alternative low-powered option to disk storage However,

NVRAMs are more expensive than disk storage devices

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3.4 Computer memory and computer storage

In this unit you will learn the differences between computer memory and computer storage Memory and storage are important concepts to master in Information Technology The two terms are sometimes used interchangeably, so it is important to understand some key differences

Computer memory needs to be quick It is constantly feeding the CPU with data to process Since nobody likes to wait for a computer, high-quality computers will have fast processors and lots of quick memory

Computers do not normally process all the information they have at once They also need to save some data for long term use This is where storage comes in Think of all the video files, mp3s, photos, documents, etc on your PC These files are not always being processed by the CPU, they are mostly just hanging around waiting to be used at some point Storage does not need to be as quick as memory, but there does need to a lot more of

it This is a key difference between memory and storage

Because memory needs to be much faster than storage, it is rather more expensive than storage per KB A typical desktop computer today (in 2009) typically has between

512 MB and 8 GB of memory running at speeds of anywhere from 300 MHZ to 1.2 GHZ Don't worry if you don't know what those measurements mean at this point We will get to them in a later unit

Memory is almost always based on semiconductor technology Examples of common computer memory include RAM, ROM, and video memory Memory is typically volatile in nature, meaning that it needs power in order to retain its state There are exceptions however, such as EPROMs, which can retain their state even when the power is off

Computer storage is typically cheaper, slower, and more plentiful than computer memory Storage comes in many different types including magnetic storage, optical

storage, and more recently semiconductor storage Storage is typically non-volatile

in nature, meaning that it retains its state even when the power is off A typical computer today comes with anywhere between 50 GB and 1 TB of computer storage

The most popular example today of magnetic storage is the hard disk drive These devices use rotating, magnetically-charged platters to store data Hard disk drives are popular because they can store a lot of data very reliably with relatively quick access times Other examples of magnetic storage devices include the tape drive and diskette Tape drives and diskettes are both good examples of legacy devices It's unlikely they will even be made much past 2010

Trends in computer storage are always changing Now it looks as if traditional magnetic hard disk drives might eventually be replaced by SSDs or solid state drives SSDs have many key advantages over magnetic storage including 1) no moving parts and 2) less power consumption This makes them very good for laptops where battery life and overall durability can be big issues If the technology continues to improve, we may even see them in desktop computers as well

Optical storage is another technology strategy used in computer storage, and

is particularly useful for sharing audio, video, and larger programs Optical storage works by a laser burning or reading data off a plastic disc coated with various types

of light sensitive material in it Due to reliability and space limitations, optical storage is seldom used as a primary means of data storage You will learn more about optical storage in later units In case you don't understand what optical storage

is, look no further than your CD-ROM, or DVD-ROM drive Here are some optical storage solutions in action!

Okay now you know the difference between memory and storage That wasn't so hard, was it?

Tiếng Anh chuyên ngành IT – Bài 3 Trang 6

Discussion Questions

1 What are the major differences between memory and storage? How much memory does

your computer have? How much storage does your computer have?

2 Do you think semi-conductor storage will ever completely replace magnetic storage?

When and why?

3 What is meant above when the author says that volatile memory needs power in order to

"retain it's state?"

Useful Vocabulary:

1 EPROM (erasable programmable read only memory)

Non-volatile (permanent) memory type that is erasable via ultra-violet light and reprogrammable

EPROMs are popular for use in critical firmware applications, such as BIOS's, because they are both non-volatile and they can be updated when necessary

2 Floppy disk drive

A legacy storage device which can read and write data slowly from a removable magnetic medium (normally 3.5" in diameter and holding 1.44 MB of data)

Floppy disk drives were once included with almost all computers, but are now considered obsolete They have been gradually replaced by DVD-R and USB drive technology

3 Hard disk drive

a storage device using rotating magnetic platters to quickly store and retrieve digital data

A hard disk drive can fail at any time, normally causing data corruption and loss So it is vitally important to have a backup routine in place

4 Magnetic storage

A storage technique using patterns of magnetized particles on a metallic surface to store data; examples include hard disk drives, tape drives, floppy disk drives

Magnetic drives have been around since the 1950's and are typically used to store large amounts of data

5 Optical storage

A data storage technique using a pattern of markings on a disc that can be read by a laser; examples include CD-ROM, and DVD-ROM technology

Optical storage is a good choice for distributing software packages because

it has a good mix of storage size, portability, and a low cost to manufacture

6 RAM (random access memory)

A type of computer memory known for being volatile (temporary) and fast

My computer was performing slowly when changing programs, so my technician installed more RAM and this solved the problem

7 ROM (read-only memory)

A type of memory which is manufactured with permanent contents which cannot be modified

The boy gave a puzzled look when the man showed him an old Atari 800 computer ROM cartridge

Tiếng Anh chuyên ngành IT – Bài 3 Trang 8

9 SSD (solid state drive)

A newer data storage device meant to replace a traditional hard disk drive; these are characterized by non-moving parts and lower energy consumption

Many new laptop models use solid-state drives, although they are more expensive and have less capacity than traditional hard disk drives

Optical storage Semiconductor storage Flash drive Diskette

In this unit you will learn about removable storage

The main idea behind removable storage is that data can be easily transferred between computers via a portable medium For many years the diskette (also known

as a floppy disk) was the best example of this kind of storage

In recent years, you are much more likely to see optical storage devices such

as CD-ROM, CD-R, DVD-ROM, and DVD-R devices being used to store larger software and data archives These devices can store between 650 MB and 50 GB of data But optical devices do have their drawbacks As you probably know, these discs scratch easily Also, optical drives have lower performance than hard disk drives, and they can normally only be written to one time with any degree of reliability

Because of the need for ever greater capacity and performance for removable storage, a new device called the flash drive has taken over the industry by storm Based on semiconductor storage technology, these devices can store up to 16 GB (or greater) of data Data read and write times are very fast due to USB 2.0 technology

As is true with most other types of computer equipment, the speed and capacity of removable storage is always increasing, while prices generally decrease for all but the newest technologies

Useful Vocabulary:

1 BD (Blu-Ray Dics)

An optical read-only disc storage media format used for data or movie storage with same dimensions as a standard DVD or CD; holds up to 50 GB or 6 times the storage of a DVD

The name Blu-ray Disc comes from blue-ish colored laser used to read and write data to this type of disc

2 BD-RE (Blu-Ray Disc Rewritable)

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An optical disc format technology which can be re-recorded multiple times Disc capacities are up to 50GB;

Blu-Ray Disc Rewritable technology holds 6 times as much data as a traditional DVD-RW They are used for high definition movie storage and to backup large file archives

3 CD –ROM (compact disc read only memory)

A storage medium popular in modern computers; one of these can hold approximately 650 MB of data

The CD-ROM has almost been completely replaced by the much more efficient DVD-ROM technology

4 CD-R (compact disc recordable)

A recordable storage medium that allows a user to write one time up to 650 megabytes of data

The nervous author backed up his novel every day on a new CD-R

5 DVD (digital versatile disc)

A portable storage medium which can hold between 4.7 and 17 gigabytes of data, often used for storing movies, games, and operating systems

The salesperson said that once he saw a film on DVD, he was never satisfied with VHS technology again

6 DVD-R (digital versatile disc recordable)

A portable recordable storage medium which allows a user to write one time up to 4.7 gigabytes of data

A DVD-R can store many times as much information as a CD-R, so they are great for making backups of larger files and folders

7 diskette

A portable magnetic storage media enclosed in a platic sleeve, typically

holding 1.4 MB of data; also known sometimes as a 'floppy disk'

Diskettes are getting rare these days and have all but been replaced by USB

flash memory drives

8 flash drive

A USB device used for portable data storage, typically 64 MB or higher; also

known as a USB drive, jump drive, and even a key drive

The man stopped using his floppy disk drive for good when he found out that

flash drives are more reliable, have more storage capacity, and are faster

9 medium

A physical transmission device or storage device of information

The purpose of software stays the same even though there is always a new medium every decade or so

3.6 Units of memory

Bit-basic units of memory

Information is processed and stored in computers as electrical signals A computer contains thousands of electronic circuits connected by switches that can

only be in one of two possible states: ON (the current is flowing through the wire)

or OFF (the current is not flowing through the wire) To represent these two conditions we use binary notation in which 1 means ON and 0 means OFF This is

only way a computer can ‘understand’ any thing Everything about computers is

based upon this binary process Each 1 or 0 is call a binary digit or bit

Tiếng Anh chuyên ngành IT – Bài 3 Trang 12

Bytes and characters

1s or 0s are grouped in to eight-digit codes that typically represent characters (letters, numbers and symbols) Eight bits together are called a byte Thus, each character

in a keyboard has its own arrangement of eight bits For example, 01000001 for the letter

A, 01000010 for B and 01000011 for C

The ASCII code

The majority of computers use a standard system for the binary representation of characters This is the American Standard Code for Information Interchange, known popularly as ‘ASSCII’ (pronounced “ask-key’ There are 256 different ways of combining

0 and 1 bits in a byte So they can give us 256 different signals However, the ASCII code only uses 128 bytes to represent characters The rest of the bytes are used for other purposes

The first 32 codes are reserved for characters such as the Return key, Tab, Escape, etc each letter of the alphabet, and many symbols (such as punctuation marks) as well as ten numbers, have ASCII representations What makes this system powerful is that these codes and standard

Kilobytes, megabytes and gigabytes

In order to avoid astronomical figures and sums in the calculation of bytes, we use units such as kilobytes, megabytes and gigabytes One kilobyte is 1,024 bytes (210) and it is represented as KB, or more informally as K one megabyte is equivalent to 1,024KB, and one gigabyte is 1,024 MB

We use these units (KB, MB, GB) to describe the RAM memory, the storage capacity of disks and the size of any application or document

Chúc Anh/ Chị học tập tốt!

Tiếng Anh chuyên ngành IT – Bài 4 Trang 1

UNIT 4: SOFTWARE

Nội dung

4.1 Definition of Software

As mentioned before,

software is another name for

programs Programs are the instructions that tell the computer how to process data into the form you want A program is a sequence of related instructions, performed one step at a time by the CPU to accomplish some tasks Programs determine how computers respond to input, what will be displayed and output There are three types of programs: system software, language interpreters and compilers and application programs

Therefore any document that you create, graphic, sound you compose, file you make, letter you write, email you send or anything that you create on your computer is referred to as software

For as long as there has been computer hardware, there has also been computer software But what is software? Software is just instructions written by programmer which tells the computer what to do Programmers are also commonly known as 'software developers', or just plain 'developers'

Nothing much is simple about software Software programs can have millions of lines of code If one line doesn't work, the whole program could break! Even the process of starting software goes by many different names in English Perhaps the most correct technical term is ‘execute', as in "the man executed the computer program." Be careful,