Magnetic disks must be protected from. In order to preserve information, floppy disks must be protected from. Email allows you to send…

Final test in computer science for 7th grade

Selected answer questions:

1. The processor processes the information provided by:

1. in decimal number system

2. in English

3. in Russian

4. in machine language (in binary code)

2. If the sanitary and hygienic requirements of the computer are not observed, the following computer device may have a harmful effect on human health:

1. printer

2. monitor

3. system unit

4. mouse

3. In order to preserve information, hard magnetic disks must be protected from:

1.reduced temperature

2. changes in atmospheric pressure

3.light

4.shocks when installing

4. In order to preserve information, flexible magnetic disks must be protected from:

1. low temperature

2. magnetic fields

3.light

4. changes in atmospheric pressure

5.in order to preserve information, laser discs must be protected from:

1.reduced temperature

2.magnetic fields

3. pollution

4.light

6. A computer program can control the operation of a computer if it is located:

1. in RAM

2.on a floppy disk

3.on CD-disk

4.on the hard drive

7.file is:

1. data in RAM

2. programs or data on a disk that have a name

3. program in RAM

4. text printed on a printer

8.When quickly formatting a floppy disk:

1. all data is erased

2. The disk is defragmented

3. The disk surface is checked

4. The disk directory is cleaned

9.When fully formatting a floppy disk:

1. all data is erased

2.The disk directory is cleaned

3. the disk becomes system

4.disk defragmentation is in progress

10.during the disk defragmentation process, each file is written:

1.in odd sectors

2.in arbitrary sectors

3.required in sequential sectors

4. in even sectors

11.When computers are turned off, all information is lost:

1. on a floppy disk

2.on the hard drive

3. on CD-disk

4.in RAM

12.system disk is required for:

1. loading the operating system

2.storing important files

3.file organization

4.treating computers from viruses

13.during the loading of the operating system the following occurs:

1.copying operating system files from a floppy disk to a hard disk

2.copying operating system files from

4.copying the contents of RAM to the hard drive

14.driver is:

1.computer device

2.program that ensures the operation of the device

3.programming language

4.application program

15.top of the hierarchical GUI folder systemWindows is the folder:

1.desk

2.disk root directory

3.my computer

4.network environment

16.raster graphic images are formed from:

1.lines

2.circles

3.rectangles

4.pixels

17.Vector graphic images lend themselves well to scaling (resizing) because:

1.high spatial resolution is used

2.they are formed from graphic primitives (lines, circles, rectangles, etc.)

3.they are formed from pixels

4. a palette with a large number of colors is used.

Answers:

1,4 2,2 3,4 4,2 5,3 6,1 7,2 8,4 9,1 10,3 11,4 12,1 13,1 14,2 15,1 16,4 17,2

A floppy disk or floppy disk is a medium of small amounts of information, which is a flexible plastic disk in a protective (plastic) shell. Used to transfer data from one computer to another and to distribute software.

In the center of the floppy disk there is a device for gripping and rotating the disk inside the plastic case. The floppy disk is inserted into the disk drive, which rotates the disk at a constant angular speed.

In this case, the magnetic head of the disk drive is installed on a certain concentric track of the disk, onto which information is written or from which information is read. The information capacity of a modern floppy disk is small and amounts to only 1.44 MB. The speed of writing and reading information is also low (only about 50 KB/s) due to the slow rotation of the disk (360 rpm).

In order to preserve information, flexible magnetic disks must be protected from exposure to strong magnetic fields (for example, do not place a mobile phone next to a floppy disk) and heat, since such physical effects can lead to demagnetization of the media and loss of information.

Currently, the most widespread are floppy disks with the following characteristics: diameter 3.5 inches (89 mm), capacity 1.44 MB, number of tracks 80, number of sectors on tracks 18 (Floppy disks with a diameter of 5.25" are now used very rarely, so their capacity does not exceed 1.2 MB, and besides, they are made of less durable material.) The floppy disk is installed in a floppy-disk drive, is automatically fixed in it, after which the drive mechanism unwinds up to a rotation speed of 360 per minute. The diskette itself rotates in the drive, the magnetic heads remain stationary. The diskette rotates only when it is accessed. The drive is connected to the processor through a floppy disk controller.

Recently, three-inch floppy disks have appeared that can store up to 3 GB of information. They are manufactured using the new Nano2 technology and require special hardware for reading and writing, which is not yet included in the standard package when purchasing a PC.

Floppy disk device

Floppy disks vary in size and capacity. By size, the division is made into floppy disks with a diameter of 5.25" (" - inch sign) and floppy disks with a diameter of 3.5". In terms of capacity - double-density floppy disks (in English double-density, abbreviated as DD) and high-density (abbreviated as HD).

A 5.25" floppy disk consists of a protective plastic sleeve containing a magnetically coated plastic disk. This disk is thin and bends easily - that's why floppy disks are called floppy disks. Of course, you cannot bend the floppy disk, and this is prevented by the protective sleeve. The floppy disk has two holes - a large one in the center and a small one next to it. The large hole is designed to allow the magnetic disk to rotate inside the envelope. This is done by a motor inside the drive. The inside of the protective envelope is covered with lint, which collects dust from the magnetic disk as it rotates. The small hole is used to count the revolutions of the disk inside the drive. The envelope has a longitudinal slot on both sides through which a disk with a magnetic coating is visible. Through this slot, a magnetic head inside the drive touches the disk and writes or reads data from it. Data is written to both sides of the disk. Never touch the surface of the magnetic disk with your fingers! By doing this, you can ruin it by scratching or greasy. If you turn the floppy disk with the slot facing you, with the label facing up, you will see a small rectangular cutout on the top right side of the envelope. If you cover it with pieces of sticky paper (usually sold with floppy disks), the disk will be write-protected. Typically, this cutout should be free; it should only be sealed on floppy disks with important data.

The design of a 3.5" floppy disk is slightly different. Its protective sleeve is made of hard plastic, so this floppy disk is more difficult to bend or break. The magnetic disk is not visible because there are no open holes. There is a slot for access of the magnetic head to the surface of the disk, but it is covered with a latch. The latch is held closed by a spring. There is no need to open it by hand to avoid damaging the magnetic disk. Inside the drive, the latch opens automatically. For write protection, the floppy disk has a small latch. You will see it at the top left of the floppy disk envelope if you hold the floppy disk with the large tab facing you, label side down. The downward position for the write latch is normal; in this state, the floppy disk is not write-protected. To prevent data from being written to the floppy disk, slide this latch upward to reveal a small square hole in the floppy disk.

Floppy disk recording method

The method of recording binary information on a magnetic medium is called magnetic coding. It lies in the fact that magnetic domains in the medium are aligned along paths in the direction of the applied magnetic field with their north and south poles. Typically, a one-to-one correspondence is established between binary information and the orientation of magnetic domains.

Information is recorded along concentric tracks (tracks), which are divided into sectors. The number of tracks and sectors depends on the type and format of the floppy disk. A sector stores the minimum amount of information that can be written to or read from disk. The sector capacity is constant and amounts to 512 bytes.

magnetic disk drive

External (long-term) memory

The main function of a computer's external memory is the ability to long-term store a large amount of information (programs, documents, audio and video clips, etc.). A device that provides recording/reading of information is called storage device, or disk drive, and the information is stored on media(for example, floppy disks).

Magnetic principle of recording and reading information. In floppy magnetic disk drives (FMD) and hard magnetic disk drives (HDD), or hard drives, information recording is based on the magnetization of ferromagnets in a magnetic field, information storage is based on the conservation of magnetization, and information reading is based on the phenomenon of electromagnetic induction.

In the process of recording information on flexible and hard magnetic disks, the drive head with a core made of soft magnetic material (low residual magnetization) moves along the magnetic layer of the hard magnetic medium (high residual magnetization). The magnetic head receives sequences of electrical pulses (sequences of logical ones and zeros), which create a magnetic field in the head. As a result, the elements of the surface of the carrier are sequentially magnetized (logical one) or not magnetized (logical zero).

In the absence of strong magnetic fields and high temperatures, the carrier elements can retain their magnetization for a long time (years and decades).

When reading information when the magnetic head moves over the surface of the carrier, magnetized areas of the carrier cause current pulses in it (the phenomenon of electromagnetic induction). Sequences of such pulses are transmitted via the highway to the computer's RAM.

Flexible magnetic disks. Flexible magnetic disks are placed in a plastic case. This storage medium is called a floppy disk. In the center of the floppy disk there is a device for gripping and rotating the disk inside the plastic case. The floppy disk is inserted into the disk drive, which rotates the disk at a constant angular speed.

In this case, the magnetic head of the disk drive is installed on a certain concentric track of the disk, onto which information is written or from which information is read. The information capacity of the floppy disk is small and is only 1.44 MB. The speed of writing and reading information is also low (only about 50 KB/s) due to the slow rotation of the disk (360 rpm).

In order to preserve information, flexible magnetic disks must be protected from exposure to strong magnetic fields and heat, since such physical effects can lead to demagnetization of the media and loss of information.

Hard magnetic disks. A hard magnetic disk consists of several dozen disks placed on one axis, enclosed in a metal case and rotating at a high angular speed (Fig. 4.6).

Due to the much larger number of tracks on each side of the disks and the large number of disks, the information capacity of a hard disk can be hundreds of thousands of times greater than the information capacity of a floppy disk and reach 150 GB. The speed of writing and reading information from hard drives is quite high (can reach 133 MB/s) due to the fast rotation of the disks (up to 7200 rpm).

Rice. 4.6. Hard magnetic disk

Hard drives use rather fragile and miniature elements (media platters, magnetic heads, etc.), therefore, in order to preserve information and performance, hard drives must be protected from shocks and sudden changes in spatial orientation during operation.

Optical principle of recording and reading information. Laser CD-ROM and DVD-ROM drives use the optical principle of recording and reading information.

In the process of recording information on laser discs, various technologies are used to create surface areas with different reflectance coefficients: from simple stamping to changing the reflectivity of areas of the disc surface using a powerful laser. Information on a laser disk is recorded on one spiral-shaped track (like on a gramophone record), containing alternating sections with different reflectivity.

Subject to proper storage (in cases in a vertical position) and operation (without causing scratches or contamination), optical media can retain information for decades.

In the process of reading information from laser disks, a laser beam installed in the disk drive falls on the surface of the rotating disk and is reflected. Since the surface of the laser disk has areas with different reflection coefficients, the reflected beam also changes its intensity (logical 0 or 1). Then the reflected light pulses are converted using photocells into electrical pulses and transmitted via the highway to the RAM.

Laser drives and disks. Laser drives (CD-ROM and DVD-ROM - Fig. 4.7) use the optical principle of reading information.

Laser CD-ROM (CD - Compact Disk) and DVD-ROM (DVD - Digital Video Disk) disks store information that was recorded on them during the manufacturing process. It is impossible to write new information to them, which is reflected in the second part of their names: ROM (Read Only Memory). Such discs are produced by stamping and have a silver color.

The information capacity of a CD-ROM drive can reach 650 MB, and the speed of reading information in a CD-ROM drive depends on the rotation speed of the disc. The first CD-ROM drives were single-speed and provided information reading speeds of 150 KB/s. Currently, 52-speed CD-ROM drives are widely used, which provide 52 times faster information reading speed (up to 7.8 MB/s).

DVDs have a much larger information capacity (up to 17 GB) compared to CDs. First, lasers with shorter wavelengths are used, which allows the optical tracks to be placed more densely. Secondly, information on DVDs can be recorded on two sides, with two layers on one side.

Rice. 4.7. CD-ROM and DVD-ROM

The first generation of DVD-ROM drives provided information reading speeds of approximately 1.3 MB/s. Currently, 16-speed DVD-ROM drives achieve read speeds of up to 21 MB/s.

There are CD-R and DVD-R discs (R - recordable) that are golden in color. Information on such disks can be written, but only once. On CD-RW and DVD-RW discs (RW - ReWntable, rewritable), which have a "platinum" tint, information can be recorded many times.

For recording and rewriting onto discs, special CD-RW and DVD-RW drives are used, which have a fairly powerful laser that allows you to change the reflectivity of surface areas during the recording process. These drives allow you to write and read information from disks at different speeds. For example, a CD-RW drive labeled "40x12x48" means that CD-R discs are written at 40x speed, CD-RW discs are written at 12x speed, and CD-RW discs are read at 48x speed.

Flash memory. Flash memory is a non-volatile type of memory that allows data to be written and stored on chips. Flash memory cards (Fig. 1.8) do not contain moving parts, which ensures high data safety when used in mobile devices (laptop computers, digital cameras, etc.).

Rice. 4.8. Flash memory cards

Flash memory is a chip housed in a miniature flat package. To read or write information, the memory card is inserted into special drives built into mobile devices or connected to a computer via a USB port. The information capacity of memory cards can reach 512 MB.

The disadvantages of flash memory include the fact that there is no single standard and different manufacturers produce memory cards that are incompatible with each other in size and electrical parameters.

Questions to Consider

1. What are the basic rules for storing and using various types of storage media?

Practical tasks

4.4. Compile a comparative table of the main parameters of information storage devices (capacity, exchange speed, reliability of information storage, cost of storing one megabyte).

Computer science tests with answers. Option 3

1) What is 1 KB equal to?

1. 1000 bits 2. 1000 bytes 3. 1024 bits 4. 1024 bytes

2) Which device has the fastest information exchange speed?

1. CD-ROM drive 2. hard drive

3. floppy drive 4. operational chips

memory

3) In order to preserve information, floppy disks must be protected from...

1. cold 2. pollution

3. magnetic fields 4. changes in atmospheric pressure

4) A system floppy disk is required for...

1. initial download 2. systematization

operating system files

3. storing important files 4. “curing” the computer

from viruses

5) The information model for organizing the educational process at school is...

1. rules of student behavior 2. class list

3. lesson schedule 4. list of textbooks

6) What will be the value of variable X after performing assignment operations:

1. 5 2. 6 3. 1 4. 10

7) In a text editor, when setting page parameters,…

1. typeface, size, style 2. indentation, spacing

3. margins, orientation 4. style, pattern

1. font size 2. file type

3. paragraph parameters 4. page dimensions

9) In spreadsheets you cannot delete...

1. column 2. row 3. cell name 4. content

10) The result of calculations in cell C1 will be:

The main function of a computer's external memory is the ability to long-term store a large amount of information (programs, documents, audio and video clips, etc.). A device that provides recording/reading of information is called a drive or disk drive, and information is stored on media (for example, floppy disks).

In floppy magnetic disk drives (FMD or floppy disks) and hard magnetic disk drives (HDD or hard drives), recording, storing and reading information is based on the magnetic principle, and in laser drives - the optical principle.

Flexible magnetic disks.

Flexible magnetic disks are placed in a plastic case. This storage medium is called a floppy disk. The floppy disk is inserted into the drive, which rotates the disk at a constant angular speed. The magnetic head of the drive is installed on a specific concentric track of the disk, onto which information is written (or read).

The information capacity of the floppy disk is small and is only 1.44 MB. The speed of writing and reading information is also low (about 50 KB/s) due to the slow rotation of the disk (360 rpm).

In order to preserve information, flexible magnetic disks should be protected from exposure to strong magnetic fields and heat, as this can lead to demagnetization of the media and loss of information.

Hard magnetic disks.

Hard disk (HDD - Hard Disk Drive) refers to non-removable magnetic disk drives. The first hard drive was developed by IBM in 1973 and had a capacity of 16 KB.

Hard magnetic disks are several dozen disks placed on one axis, enclosed in a metal case and rotating at high angular speed. Due to the many tracks on each side of the disks and the large number of disks, the information capacity of hard disks can be tens of thousands of times greater than the information capacity of floppy disks and reach hundreds of GB. The speed of writing and reading information from hard drives is quite high (about 133 MB/s) due to the fast rotation of the disks (7200 rpm).

A hard drive is often called a hard drive. There is a legend explaining why hard drives got such a fancy name. The first hard drive, released in America in the early 70s, had a capacity of 30 MB of information on each working surface. At the same time, O. F. Winchester's repeating rifle, widely known in America, had a caliber of 0.30; Maybe the first hard drive rumbled like a machine gun during its operation, or it smelled of gunpowder - it’s not clear, but from then on they began to call hard drives hard drives.

During the operation of the computer, malfunctions occur. Viruses, power outages, software errors - all this can cause damage to information stored on your hard drive. Damage to information does not always mean its loss, so it is useful to know how it is stored on the hard drive, because then it can be restored. Then, for example, if the boot area is damaged by a virus, it is not at all necessary to format the entire disk (!), but, having restored the damaged space, continue normal operation while preserving all your invaluable data.

Hard drives use fairly fragile and miniature elements. To preserve information and the performance of hard drives, it is necessary to protect them from shocks and sudden changes in spatial orientation during operation.

Laser drives and disks.

In the early 80s, the Dutch company Philips announced a revolution in the field of sound reproduction. Its engineers came up with something that is now extremely popular - laser discs and players.

Over the past few years, computer compact disc (CD) readers, called CD-ROMs, have become an almost essential part of any computer. This happened because various software products began to take up a significant amount of space, and delivering them on floppy disks turned out to be prohibitively expensive and unreliable. Therefore, they began to be supplied on CDs (the same as regular music ones).

Laser disk drives use the optical principle of reading information. On laser discs CD (CD - Compact Disk, compact disc) and DVD (DVD - Digital Video Disk, digital video disc), information is recorded on one spiral-shaped track (like on a gramophone record), containing alternating sections with different reflectivity. A laser beam falls on the surface of a rotating disk, and the intensity of the reflected beam depends on the reflectivity of the track section and acquires values ​​of 0 or 1. To preserve information, laser disks must be protected from mechanical damage (scratches), as well as from contamination. Laser discs store information that was recorded on them during the manufacturing process. It is impossible to write new information to them. Such discs are produced by stamping. There are CD-R and DVD-R discs on which information can only be written once. On CD-RW and DVD-RW discs, information can be written/rewritten many times. Disks of different types can be distinguished not only by markings, but also by the color of the reflective surface.

Burning to CDs and DVDs using regular CD-ROMs and DVD-ROMs is not possible. To do this, you need CD-RW and DVD-RW devices with which read-once write and read-write-rewrite are possible. These devices have a fairly powerful laser that allows you to change the reflectivity of surface areas during the recording process. The information capacity of a CD-ROM reaches 700 MB, and the speed of reading information (up to 7.8 MB/s) depends on the disk rotation speed. DVD discs have a much larger information capacity (single-layer single-sided disc - 4.7 GB) compared to CD discs, because lasers with a shorter wavelength are used, which allows the optical tracks to be placed more densely. There are also dual-layer DVDs and double-sided DVDs. Currently, the reading speed of 16-speed DVD drives reaches 21 MB/s.

Devices based on flash memory.

Flash memory is a non-volatile type of memory that allows data to be written and stored on chips. Devices based on flash memory do not have moving parts, which ensures high data security when used in mobile devices.

Flash memory is a chip housed in a miniature package. To write or read information, drives are connected to a computer via a USB port. The information capacity of memory cards reaches 1024 MB.