External computer memory. Various types of storage media, their characteristics (information capacity, speed, etc.)
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.). The device that provides recording/reading of information is called a drive or disk drive, and information is stored on media (for example, floppy disks).
Floppy magnetic disks(NGMD, floppy disk, floppy disk) – a medium of small amount of information on a flexible plastic disk in a protective shell. The disk is coated on both sides with magnetic oxide. Recording method: magnetic encoding. Information is recorded along concentric tracks - tracks that are divided into sectors. The sector capacity is constant and equal to 512 bytes. Floppy disk diameter 3.5 inches (89 mm). When formatting, each side of the disk is divided into 80 tracks and 18 sectors. That's why capacity floppy disks 80*18*512*2= 1.4MB(actually 1.38 MB). Information is recorded and read by magnetic heads. Speed disk rotation is slow - 360 rpm (6 per second). The disk rotates only when being handled. Data reading speed is 50KB per second. Floppy drives required protect from magnetic fields and heating.
Hard magnetic disks(HDD-hard disk drive, hard drive) – large storage device containers - up to 400GB. It consists of several dozen metal disks placed on one axis, enclosed in a housing. Speed writing and reading - 133 MB per second, disk rotation speed 7200 rpm. The disks rotate continuously while the computer is running. Due to the fragility of the internal elements (heads, plates, etc.), the hard drive must protect from blows.
Optical discs(laser, CD - compact discs, DVD-digital video discs:
CD-ROM(read only memory) - read-only disk, appeared in 1986, capacity 780 MB (500 floppy disks), transparent polymer disk with a diameter of 12 cm, thickness 1.2 mm. One side has a reflective layer of aluminum coated with a layer of varnish. To create a CD-ROM, metal die stamping is used. When stamping, pits appear on the surface of the plastic - depressions are 0, spaces between pits are 1). Information is recorded on one spiral-shaped track starting at the axis (there are 16 thousand turns of the spiral at every inch of 2.54 cm).
CD-R(recordable) for one-time recording, blank, 700 MB. The main plastic layer contains no information, just an empty track to guide the laser beam. The second layer is a film of organic molecules (cyanites), then metal and varnish. When heated by a powerful laser beam, the molecules change their optical properties (they stop transmitting light), forming pits.
CD-RW(rewritable) for multiple recording, several GB. Instead of organic molecules there is a film of rare metal alloys. When heated, the metal goes into an amorphous state and remains in it, forming pits - areas that poorly reflect light. When the same area is heated again, the metal returns to its original state. (several thousand times).
DVD-ROM, DVD-R, DVD-RW. Capacity up to 17 GB. They can be double-sided or double-layered. The spiral turns are more frequent, the pits are smaller, since a laser beam with a shorter wavelength is used to record and read information.
To read information, a laser beam is used, which is directed to the surface and reflected. The reflected light pulses (which have different intensities due to the heterogeneity of the disk surface) are converted into electrical pulses using photocells.
Flash memory – non-volatile type of external memory, is a microcircuit in a housing, connected to a USB port. Capacity - several GB.
In developing FMD (fluorescent multilayer dick) – fluorescent multilayer disk. Contains 10 layers, diameter 5 inches, capacity 140GB. Completely transparent, made of polycarbonate. Consists of cells (pits) filled with organic matter (photochrome) that can emit light. Future– behind the multi-layeredness and volume – three-dimensional holography.
Some technical characteristics of various information storage devices are essential for the user: information capacity, speed of information exchange, reliability of its storage.
9. Functional diagram of a computer. Basic computer devices, their purpose and relationship.
CPU. The processor can process various types of information: numerical, text, graphic, video and audio. The processor is an electronic device, so various types of information must be processed in it in the form of sequences of electrical impulses.
Such sequences of electrical pulses can be written as sequences of zeros and ones (there is a pulse - one, no pulse - zero), which are called machine language.
Information input and output devices. A person does not perceive electrical impulses and very poorly understands information presented in the form of sequences of zeros and ones; therefore, the computer requires special input and output devices.
Input devices “translate” information from human language into computer machine language, and output devices, on the contrary, make information presented in machine language accessible to human perception.
Information input devices. Numerical and text information is entered using the keyboard. To enter graphic information or work with the graphical interface of programs, manipulators such as a mouse (for desktop personal computers) and a trackball or touchpad (for laptop computers) are most often used.
If we want to enter a photograph or drawing into the computer, we use a special device - a scanner. Currently, digital cameras (photo and video cameras), which generate images in computer format, are becoming increasingly widespread. To input audio information, a microphone is used, connected to the input of a special sound card installed in the computer.
It is more convenient to control computer games using special devices - game controllers (joysticks).
Information output devices. The most universal output device is a monitor, on the screen of which numerical, text, graphic and video information is displayed.
A printer is used to save information in the form of a “hard copy” on paper, and a plotter is used to display complex drawings, drawings and large-format diagrams on paper.
Sound information is output using speakers or headphones connected to the sound card output.
Working and long-term memory. In a computer, information is stored in RAM (internal) memory. However, when you turn off the computer, all information from RAM is erased.
Long-term storage of information is provided by external memory. External memory devices typically include floppy disk drives (FMDs), hard disk drives (HDDs), and optical drives (CD-ROM and DVD-ROM).
Highway. Information is exchanged between individual computer devices via a highway (Fig. 8).
Connecting your computer to the network. A person constantly exchanges information with people around him. A computer can exchange information with other computers using local and global computer networks. To do this, it includes a network card and a modem.
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). up to a rotation speed of 360 per minute. The diskette itself rotates in the drive, the magnetic heads remain stationary. The drive is connected to the processor through the 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 (in English, abbreviated as DD) and high-density (abbreviated as HD) floppy disks.
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
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:
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 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
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.
|
Media type |
Media capacity |
Data transfer speed (MB/s) |
Hazardous influences |
|
Magnetic fields, heating, physical influence |
|||
|
hundreds of GB |
Impacts, changes in spatial orientation during operation |
||
|
650-800MB |
Scratches, dirt |
||
|
up to 17GB | |||
|
Flash Memory Devices |
up to 1024 MB |
USB 1.0 - 1.5 USB 1.1 - 12 USB 2.0 - 480 |
Power overvoltage |