Bài tập tiếng Anh chuyên ngành Công nghệ thông tin - Lê Thị Hồng Hạnh

Nội dung text: Bài tập tiếng Anh chuyên ngành Công nghệ thông tin - Lê Thị Hồng Hạnh

1. Câu hỏi 3. Why are IPO charts a good way to describe a system? 4. Making a piece of buttered toast is a system. Draw an IPO chart to describe this system. 5. Planting a tree bought at the nursery is a system. Draw an IPO chart to describe this system. 6. The recorded music system involves using a record, cassette or compact disc to listen to music. Draw an IPO chart to describe this system. Câu 7: Specifying procedures Procedures are the set of instructions which specify what processing is to be performed. These procedures are essential if the system is going to achieve its purpose and are stated in the form of an algorithm. An algorithm is a series of steps which, when performed correctly, will solve a problem in a finite time. Algorithms can be used to solve all kinds of problems. Even simple actions such as making a phone call, catching a train or running a shower can be represented as algorithms. The algorithm to make a phone call might be: 1. Pick up the phone receiver. 2. Dial the correct phone number 3. Deliver the message 4. Hang up the phone receiver. , The algorithm presents a solution in a finite number of steps. The algorithm to catch a train takes five steps. For the algorithm to work in all situations, the steps must be performed in a particular order and the algorithm must describe every possibility that may occur. Before the algorithm can be written, the problem must be fully understood. After the algorithm has been written it needs to be tested. If the results are unsatisfactory it is modified or discarded. There is usually more than one correct algorithm to any problem and the best algorithm is a matter of personal choice. 1 Write down whether the following statements are true or false. a. Algorithms contain an infinite number of steps. b. Algorithms always need to be tested. c. A problem may be solved by more than one correct algorithm. d. Procedures are not stated in the form of algorithms. e. We use algorithms all the time. f. Unsatisfactory algorithms are always discarded. g. The steps in an algorithm are sometimes repeated. h. Algorithms do not allow for decisions to be made. 2. What is an algorithm? 3. Explain the difference between procedures and an algorithm. 4. What needs to be done if an algorithm is unsatisfactory? 11
2. Câu hỏi Câu 8: Algorithms Algorithms are used to enable computers to 'solve particular problems and perform a variety of tasks. This involves a number of stages: first, the problem is analysed to determine its essential features. Secondly, the algorithm is written to solve the problem. Thirdly, the algorithm is changed into a programming language which can be understood by the computer. . In order for the algorithm to be easily changed into a programming language, it needs to be written in a particular form. Algorithms can be expressed in a number of forms including English prose pseudocode and flowcharts. ENGLISH PROSE English prose is a description of the steps required to solve the problem in plain English without a structure. English prose is the simplest method of algorithm description, but since there are no formal rules it is difficult to apply it to complex problems. PSEUDOCODE Pseudocode is a limited form of English which relies on indenting lines and using keywords to highlight the structure of the algorithm. It is written in text form which allows it to be easily modified with a word processor. Different standards of psuedocode have been established for different applications. The basic keywords are grouped together in pairs. The most common keywords are shown in the table on the following page. Structured English is another method of describing algorithms which is very similar to pseudocode. It does not use any keywords, but consists of short statements with indentation to show the structure. FLOWCHARTS Flowcharts are a way of describing algorithms in pictorial form. They are often favoured since it is easier to follow the structure in a picture than in words; however, it is very easy to draw a flowchart which is complex and difficult to change into programming language. The basic elements of a flowchart are a set of symbols (containing messages) and interconnecting lines with arrows: A set of standards for flowcharts has been established for a number of different. applications. The four most commonly used symbols are shown in the following table. 1. For each of the following statements, select a matching phrase from the list below. a. Lines and arrows used in flowcharts. b. An algorithm which uses a limited form of 'English and relies on indentation and keywords. c. A symbol used in flowcharts to indicate a selection. d. An algorithm in pictorial form which uses a set of symbols and flowlines. e. An algorithm which uses an English description of the steps required to solve the problem. f. A symbol used in 'flowcharts to indicate the beginning or the end. g. Used to show the structure in pseudocode. 12
3. Câu hỏi h. Algorithms are converted into this language so that they can be understood by the computer. i. A series of steps which, when performed correctly; will solve a problem in a finite time. flowlines terminal indentation algorithm flowchart programming pseudocode decision English prose 2. Briefly describe the following methods of algorithm description: a. English prose b. flowcharts c. pseudocode. 3 .Why are flowcharts often favoured as a method of describing algorithms? 4. When is it necessary for flowlines to have arrows? 5.Write down two advantages pseudocode has over flowcharts. 6 .Why are keywords high lighted in pseudocode? 7. What is the purpose of indenting lines in structured English and pseudocode? 8. Write algorithms in English prose, pseudocode and as a flowchart for the following: a making a cheese sandwich b making corn flakes for breakfast. Câu 9: Control Structures Control structures are used in an algorithm to control the flow of logic; that is, they indicate the order in which the statements are carried out. Algorithms are composed of three basic control structures: sequence/ selection and loop. SEQUENCE Sequence is where the steps are executed' one after another. Each statement is performed only once and is then fol1owed by the next statement in order. Example: Washing your hands 13
4. Câu hỏi SELECTION Selection allows for different steps to be carried out in different conditions. There are many situations when the normal sequence of one step: followed by the next is not appropriate. Using selection, a condition such as a question can be given and, depending on the answer, different steps can be followed. Example: Approaching a set of traffic lights English prose If the signal is green, pass through the traffic lights; otherwise stop the vehicle. Pseudocode Begin if signal is green then pass through, traffic lights else stop the vehicle end if 14
5. Câu hỏi LOOP A loop or repetition allows a number of steps to be repeated until some condition is satisfied. It is very important that each loop includes a condition that will stop the loop going on forever. If the condition is checked at the beginning of the loop, it is called a pre-test loop or guarded loop. Example: Safety procedure for traveling in a car English prose Keep seat belts on while you are' traveling in the car. Pseudocode Begin While car is traveling Seat belts on End while End If the condition is checked at the end of the loop, it is called a post-test loop or unguarded, loop. Example: Watering plants English prose Keep watering the plants until the ground is soaked. Pseudocode Begin Repeat . Water plants Until ground is soaked End 1) The vowels have been omitted from these words. Write out the completed words a. s_q _ _ nc _ b. fl _ wch _ rt c. s _ l _ ct _ _ n 15
6. Câu hỏi d. r _ p _ t _ t _ _ n e. g _ _ rd _ d l _ _ p f. ps _ _ d _ c _ d _ g. c _ ntr _ l str _ ct _ r _ s h. _ ngl _ sh pr _ s _ i. _ ng _ _ rd _ d l _ _ p j. fl _ wl _ n _ s 2. What are control structures used for? 3. Explain the difference between the following control structures: sequence, selection and loop Câu 10: Review Exercise 1 1. Copy and complete the following sentences. a. A . is a system whose internal components are not fully understood. b. The boundary is the - of a system. c. Procedures are a set of which specify what processing is to be performed. d. charts are used to show the levels of refinement of a process. e. A system is a group of elements which work together to achieve a f. Refinement breaks down . systems into smaller sub-systems. g. Output is something taken the system. h. The . is the physical conditions or surrounding influences within which the system operates. i. charts are a way of describing a system by specifying inputs, processes and outputs. j. Resources are used by the to perform its task. k. A is a small system which is part' of a larger system. l. A process is a series of carried out by the system. m. Control structures indicate the in which the statements are executed. n is a control structure that allows for different steps to be carried out in different conditions. o. A flowchart describes an algorithm in and flowlines. p. An algorithm is a series of which, when performed correctly, will solve a problem in a finite time. . q .describes the steps in an algorithm using plain English. r. A loop is a control structure that allows a number of steps to be until some condition is satisfied. s. Pseudocode describes an algorithm using a limited form of English. It relies on indentation and the use of t . .is a control structure in which the steps are executed one after another. 2. Turning on the TV and watching your favourite TV show can be considered as a 16
7. Câu hỏi system. a Construct an IPO chart for this system. b List any procedures, resources and processors used in the process. c What is the system's boundary and environment? 3. Why do systems undergo refinement? 4. What is the difference between the boundary of a system and its environment? 5. How are the procedures, processor and resources related in a system? 6. Explain the difference between hierarchy charts and IPO charts. 7. Why are algorithms written? 8. List three methods of describing an algorithm. 9. Describe the three basic control structures. Câu 11: A computer system A computer can be considered as a system made up of hardware and software, which work together, processing data to achieve a purpose. Computer hardware refers to the parts of the computer system that you can see and hold, such as the keyboard, monitor, disk drive or printer. Computer software refers to the computer programs or instructions which direct the hardware to perform particular tasks. Computer systems can be viewed as five co-operating sub-systems. Input - entering data into the system for processing. Output - presenting data/information which can be used outside the system Processing - changing data to produce information Storage - retaining data for later use by the system. Control - coordinating the operations of the input, processing, output and storage sub- systems. These sub-systems work together. Data is entered using an input device. It is then changed in some way to produce information, which is presented on an output device. If necessary, the data/information can be retained on a storage device for later use. To process the data the hardware needs dear instructions, or software, which tell it what to do. 1. Copy and complete the following sentences. a. Output involves the data/information. b. Computers can process information at very . speed. c. Processing involves . data to produce information. d. Storage involves . data for later use. e. The instructions given to a computer so that it can perform a particular task are called its f. . involves co-ordinating the operations of the input, processing, output and storage sub-systems. g. Parts of the computer system that you can see and touch are called its 17
8. Câu hỏi h. A computer system is made up of hardware and software which 'work together, processing data to achieve a i. involves entering data into the system for processing. j. The computer software refers to the computer program or which direct the hardware to perform particular tasks. 2. What is a computer? 3. What is the purpose of a computer system? Câu 12: Input Input involves entering data into the system for processing. The data is taken from the environment and changed into a suitable form to be processed. There are many types of input devices used for different purposes. The two most common input devices are the keyboard and the mouse. THE KEYBOARD A computer keyboard looks similar to a typewriter, with a number of extra keys for special purposes. Data is entered when one or more keys are pressed to represent a character or special function. If a key representing a character is pressed, the character appears where the blinking rectangle, or cursor, is on the screen. The cursor indicates the user's current position on the screen. The keyboard is the main device that you use to communicate with your computer. Some of the special keys include: Enter or Return - used to inform the computer to act on an instruction (command) or to move the cursor to a new line. - allows you to stop the execution of a command. - used in combination with other keys to perform special tasks. - used in a similar way to the control key (not found on all keyboards). THE MOUSE A mouse is a pointing device that can be used to point the cursor at the desired position on the screen. It enables the -user to move the cursor to different parts of the screen very quickly. A button on the mouse allows the user to select a character or command from the screen display. Other common input devices include the light pen, joystick, scanner, touch screen and trackball. 1. Write down whether the following statements are true or false a. The mouse does not allow the user to move the cursor quickly. b. Input devices take data from the computer system. c. The cursor indicates the user's current position on the screen. d. Data can be entered into the computer using a keyboard. e. The mouse is part of the computer's software. f .Computers do not have any intelligence. 18
9. Câu hỏi g. The software follows instructions contained in a computer's hardware which command it to perform a particular task. h. The Escape key allows you to stop the execution of a command. i .The Enter or Return key is used in combination with another key to perform a special task. j. The Backspace key deletes the character immediately to the left of the cursor. 2 .Make a drawing of the keyboard used on the computers at school. Mark the standard typewriter keys and the special computer keys. Try pressing the various keys to learn what they do. . 3 .What is the long key across the bottom used for? Câu 13: Output Output involves presenting data/information which can be used outside the system. Computers present data to users as text (letters and numbers) or graphics (pictures), or in the form of computer-generated speech called voice synthesis. Many kinds of output devices can be used to present data.The two most common output devices are the monitor and the printer. The monitor The monitor is the most popular output device. It is similar to a television screen, but superior in clarity. The monitor is known by several names which include the screen, CRT (cathode ray tube) or VDU (visual display unit). There are many types of monitors and they can be either monochrome or colour. Monochrome refers to black on white or, in some cases, amber or green on black. Many laptop computers and portable computers use a liquid crystal display (LCD), the same type of display as on digital watches and calculators. This type of display is very light and requires less power than a CRT, allowing it to be run on batteries. The printer A allows data to be presented on paper as a 'hard copy' or printout. There are many different types of printers, the main types being dot-matrix, ink-jet and laser. The dot-matrix printer is the cheapest and most popular. A printer must have power, be connected to the computer and have the paper inserted correctly. The computer's software must be instructed about the type of printer being used. 1. For each of the following statements, select a matching word or phrase from the list below. a. Devices used to enter data into a computer system for processing. b. Screen used by many laptop computers. c. A type of monitor that comes in black and white, black and amber or black and green. d. Devices used to present data. e. An input device which consists of a series of keys which produce characters when pressed. f. The physical components of a computer system. g. The most popular type of printer. 19
10. Câu hỏi h. A key on a keyboard used to inform the computer to act on an instruction. i .A key on a keyboard that allows you to stop the execution of a command. dot matrix output LCD Enter monochrome input keyboard hardware Escape 2. Why are LCD screens used on laptop computers instead of CRT monitors? 3. What is the main difference between a computer monitor and a television set in presentation of data? 4. In what forms do computers present data to users? 5. What would you check if a printer was not working correctly? Câu 14: Processing Processing changes data to produce information. Data are the raw facts put into the computer system by an input device. When this data is processed or ordered and given some meaning, it is called information. This information is then presented for use outside the system by an output device. The processing in a computer is carried out by the central processing unit or CPU. It is made up of millions of electrical components and is the control centre of the entire computer system. The electrical components are located on a thin silicon wafer called a silicon chip or integrated circuit. The CPU in a microcomputer is referred to as a microprocessor and is contained on one silicon chip. 1. Vowels have been omitted from these words. Write out the completed words. a. s-l-c-n ch-p f. –nt-gr–t-d c-rc- -t b. m-cr -_pr-c-ss-r g. l-pt-p c. m- n- t - r h. d-t- d. -nf - rm-t- -n i. d-v-c-s e. pr-c-ss j. – nstr - ct- -n 2. What does the central processing unit do? 3. How is data changed into information? 4. Microprocessors are being used in many different ways. Write down five pieces of equipment. in which a microprocessor is used. 5. If possible, under teacher supervision, examine the internal parts of the school's computer. Find the CPU. Câu 15: Storage Storage involves retaining data for later output or processing by the system. Data can be stored for later processing in primary storage or stored for later use. Primary storage, or main memory, is the computer's internal data storage area. It is directly linked to the CPU and stores data before and after it is processed. The unit of measurement of storage is the byte and it represents a single character, such as a letter, a number, a punctuation 20
11. Câu hỏi mark or a space. Primary storage can be measured in billions of bytes (gigabytes), millions of bytes (megabytes) or thousands of bytes (kilobytes), depending on the capabilities of the computer. Since primary storage is generally limited in size and is often too small to contain all the necessary data, most computers use secondary storage. A common form of secondary storage device is the magnetic disk. Data can be stored on and recalled from either a hard disk or a floppy disk. Disks Hard disks and floppy disks are magnetic disks whose surface has been coated with a thin layer of iron oxide. They are housed in protective jackets or containers, since a fingerprint, spot of dust, or smoke particle can prevent access to the data on the disk. Floppy disks are cheap and vary in size from 9-20 cm; the most popular standard sizes are the 3.5 inch (9 cm) and the 5.25 inch (13 cm). The 5.25 inch disks are 'floppy', as their name suggests, but the 3.5 inch disks are housed in a hard plastic jacket. To be used, a floppy disk must be inserted into the right sized disk drive. The floppy disk drive is either built in to the computer or is an external unit connected to it by a cable. The disk drive spins the disk at a constant speed and data is read from or written to 'tracks' located on the surface of the disk. . With proper care and handling floppy disks are usable for many years, with no loss of data. To insure against data loss, the disk must be protected from damage, contamination and exposure to magnetic fields. It only takes a tiny particle to affect data transfer and cause errors. In order to protect your floppy disks, follow these safety precautions. . Keep floppy disks in a protective envelope when not in use. . When transporting or posting disks, always use a protective box. . Never expose disks to temperatures above 50 °C or below 10°C. Temperatures inside a car can exceed 50 °C on a hot day. . Magnetic fields destroy data on your disk. Magnetic influence can be caused by any magnet, monitor, disk drive or electronic appliance that generates a magnetic field. Always store your disks in storage boxes at least 10 cm from all electrical appliances or computer components. A hard disk works on the same principles as a floppy disk except that it is rigid and much thicker, and spins much faster. It is usually housed in a special casing inside the computer and is not removed like a floppy disk. Hard disks hold much more data than floppy disks. 1. Write down whether the following statements are true or false. a. Secondary storage is limited in size and is often too small to contain all the necessary data. b. Floppy disks should be kept in their. protective envelope when not in use. c .Hard disks hold less data than floppy disks. d. Magnetic fields do not destroy data on floppy disks. e. Data is stored for later processing in primary storage. f .Magnetic disks should not be kept near any device that generates a magnetic field . 21