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e. process j. instruction
2. CPU carry out the processing in a computer. 3. 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.
Câu 15:
1. Write down whether the following statements are true or false. a. F b. T c .F d. F e. T f .T
2. primary storage is generally limited in size and is often too small to contain all the necessary data, most computers use secondary storage.
3. 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.
4 .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. 5 .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.
Câu 16:
1. e. computer a.microcomputer c. microprocessor
b.tiny d.supervisor
2. The control unit doesnt process data itself, but selects, interprets and oversees the execution of the programs instructions. It controls all the parts of the computer system, just as the
central nervous system controls the muscles and other parts of the human body. 3. central processing unit
4 .The number of these electrical pulses per second indicates the speed of the processor.
Câu 17:
1. Copy and complete the following sentences.
a. A hacker is a person who gains illegal access to a computer system from her or his
personal computer. b. Secret words or numbers to gain access to a computer system are referred to as
password c. The process of decoding and encoding data is called cryptography
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d. Security involves a system of safeguards designed to protect a computer system and
its data.
e. The loss of data is the major concern in the security of a computer system. f. The weakest link in the security of any computer system is the people in it.
g. Security of data could include internal controls where a list is kept of every time someone
has gained access to certain data.
h. Loss of software is not a problem if backup copies of software have been kept. i . Shredders are used to destroy waste.
2.The loss will probably be covered by insurance and the equipment can be replaced. 3. Waste must be secured since discarded printouts, printer ribbons and the like can be
sources of information to unauthorised persons. This kind of waste can be destroyed using shredders. Passwords are secret words or numbers that must be typed on the keyboard to gain
access to the system. Good data protection systems change passwords often so that only authorised persons can have access to certain data.
. Internal controls are controls that are planned as part of the computer system. For example, the computer system could keep a list of every time someone has gained or attempted to
gain access to certain data. . Data sent over communication lines can be encoded cryptography. The code can only be
decoded by the person who is to receive the data. . The weakest link in the security of any. computer system is the people in it. Employees
need to be screened carefully. Dishonest job applicants should not be employed. There are a number of ways to restrict data to authorised persons.
4. There are a number of ways to restrict data to authorised persons. These include using a key, badge, plastic card, password, identification number, personal signature, and devices which
recognise individual body characteristics such as fingerprints and voice. Some systems use a combination of the above techniques. For example, access to an
automatic teller machine requires both a plastic card and a personal identification number.
Câu 18: REVIEW EXERCISE
1. Copy and complete the following sentences.
a. The monitor is the most popular form of output device. b. To obtain a hard copy output a printer is needed.
c. The physical equipment that makes up the computer system is referred to as hardware d .The cursor is generally a rectangle the size of a capital letter which appears sometimes
flashing on the screen of a monitor to indicate the current display position.
e.Devices used to present data are called output devices f. A common form of secondary storage device is a disks
g. The processing in a computer is carried out by the CPU h. A type of computer screen that is similar to a television set is called a monitor
i Devices used to enter data are called input devices.
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j Monitors tare available in monochrome or colour.
2. input, output, processing, storage, control. 3. floppy disks vary in size from 9-20 cm, the most popular standard sizes are 9cm and
13cm. the floppy disk can be removed and cheap.
4. a. Monitor is the most popular output device. b. Mouse is a pointing deice that can be used to point the cursor at the desired position on
the screen. c. Key board is the main device that you use to communicate with your computer.
d. to be used, a floppy disk must be inserted into the right size disk drive. It spins the disk at a constant speed and data is read from or written to tracks located on the surface of the disk.
5. Because primary storage is limitted in size. 6. The control unit uses a system clock to synchronise all the tasks by sending out electrical
pulses. The number of these electrical pulses per second indicates the speed of the processor.
Câu 19:
1. Copy and complete the following sentences.
a. Supercomputers are mainly used in scientific applications. b. Pre-packaged chip is available, so that microcomputers are easy to use.
c. Mainframe computers can accommodate input from 1000 workstations or terminals. d. A billion bytes of data is referred to as a gigabytes
e. A minicomputers is a general purpose computer that calculates at rates from 5 to 50
