COMPUTER
1. What is input device?
Ans. Input device:
In short, those devices which are used for getting data from the user to the computer are called input devices.
Actually input device is a device (peripheral device) that generates input for the computer such as a keyboard, scanner and mouse or digitize tablet.
We can also say that, input device is used to insert data into a computer, or any machine that feeds data into a computer called input device.
2. List different types of input devices;
Ans. List of input devices:
I. Keyboard;
II. Mouse;
III. Light pen;
IV. Scanner;
V. Game pad;
VI. Camera;
VII. Touch pad;
VIII. Kiosk;
IX. Microphone;
X. OMR;
XI. OCR;
XII. Barcode reader;
XIII. Track ball;
XIV. Digital camera;
XV. Remote control;
XVI. Stylus;
XVII. Card reader;
XVIII. Power glove;
XIX. Wii remote;
XX. Bluetooth pan;
And many more;
3. Describe different types of optical input device;
Ans. Different types of optical input device:
There are different types of optical input devices, some of them are described below…..
Scanner:
There was a time when the only way to transfer as existing document into the computer was to retype it. Now, however, an optical scanner usually referred to as a scanner, can convert text or even a drawing or picture into computer – recognizable data by using a form of optical recognition.
Large business often use a process called document imaging, in which a scanner converts all incoming paper documents, such as invoices and order forms, to electronic versions, which can then be stored on disk, routed to the proper people, and retrieved when needed. Business people imaging useful because they can view an exact computer – produced replica of the original document at any time. Processed by related software, the words and numbers of the document can be manipulated by word – processing & other software.
OMR:
Optical Mark Recognition (also called Optical Mark Reading and OMR) is the process of capturing human-marked data from document forms such as surveys and tests.
Many traditional OMR devices work with a dedicated scanner device that shines a beam of light onto the form paper. The contrasting reflectivity at predetermined positions on a page is then utilized to detect the marked areas because they reflect less light than the blank areas of the paper.
Some OMR devices use forms which are preprinted onto paper and measure the amount of light which passes through the paper, thus a mark on either side of the paper will reduce the amount of light passing through the paper.
OCR:
OCR (Optical Character Recognition) devices can read special characters & convert them into electrical signals to be sent to the central processing unit by using a light source. Actually it’s an electronic device which is used to recognize printed or written letters or numbers or special characters. These characters are often found on sales tags on store merchandise.
Barcode reader:
Each product on the supermarket shelf has its own unique number, which is a part of the Universal Product Code (UPC). This code number is represented on the label by a pattern of vertical marks or bars called bar codes. These stripes can be sensed & read by a photoelectric device that reads the code by means of reflected light, which is called barcode reader.
Bar coding has been described as an inexpensive & remarkable reliable way to get data into a computer.
Light pen:
A light pen is a computer input device in the form of a light-sensitive wand used in conjunction with a computer's CRT TV set or monitor. It allows the user to point to displayed objects, or draw on the screen, in a similar way to a touch screen but with greater positional accuracy. A light pen can work with any CRT-based display, projectors and other display devices but not with LCD screens.
A light pen is fairly simple to implement. The light pen works by sensing the sudden small change in brightness of a point on the screen when the electron gun refreshes that spot. The pen position is updated on every refresh of the screen.
Graphics tablet:
A graphics tablet (or digitizing tablet, graphics pad, drawing tablet) is a computer input device that allows one to hand-draw images and graphics, similar to the way one draws images with a pencil and paper. These tablets may also be used to capture data or handwritten signatures.
Optical tablets operate by a very small digital camera in the stylus, and then doing pattern matching on the image of the paper.
Some tablets are intended as a general replacement for a mouse as the primary pointing and navigation device for desktop computers.
Touch screen:
A touch screen is a display that can detect the presence and location of a touch within the display area. The term generally refers to touch or contact to the display of the device by a finger or hand. Touch screens can also sense other passive objects, such as a stylus. However, if the object sensed is active, as with a light pen, the term touch screen is generally not applicable. The ability to interact directly with a display typically indicates the presence of a touch screen.
4. How does keyboard work?
Ans. How a keyboard works:
When a press a key:
Ø The keyboard controller detects the keystroke;
Ø The controller places a scan code in the keyboard buffer, indicating which key was pressed;
Ø The keyboard sends computer an internet request, telling the CPU to accept the keystroke.
v The illustrator is in the lecture sheet, given by the teacher;
5. Write the functions of barcode reader;
Ans. Functions of barcode reader:
i. Practically every item purchased from a grocery store, department store, and mass merchandiser has a UPC barcode on it. This greatly helps in keeping track of the large number of items in a store and also reduces instances of shoplifting;
ii. Document management tools often allow for bar coded sheets to facilitate the separation and indexing of documents that have been imaged in batch scanning applications;
iii. The tracking of item movement, including rental cars, airline luggage, nuclear waste, mail and parcels;
iv. Many tickets now have barcodes that need to be validated before allowing the holder to enter sports arenas, cinemas, theatres, fairgrounds, transportation etc;
v. Used on automobiles, can be located on front or back;
vi. Recently, researchers have placed tiny barcodes on individual bees to track the insects' mating habits;
vii. At the turn of the century, many artists started using barcodes in art.
6. What is output device?
Ans. Output devices:
Output devices are things we use to get information out of a computer. An output device is any piece of computer hardware equipment used to communicate the results of data processing carried out by an information processing system to the outside world.
We can also say any machine capable of representing information from a computer is called output device. This includes display screens, printers, plotters, and synthesizers.
7. Describe different types of monitor; / Compare CRT & Flat-panel display;
Ans. Different types of monitor:
Monitors are categorized by the technology they use; by depending on the technology there are mainly two types of monitor….
a. Cathode ray tube (CRT) monitors;
b. Flat-panel displays;
a. CRT monitors:
Ø In CRT monitors, electrons are fired at phosphor dots on the screen;
Ø The dots are grouped into pixels, which glow when struck by electrons;
Ø In color CRTs each pixel contains a red, green & blue dot. These glow at varying intensities to produce color images.
b. Flat-panel monitors:
Ø Most flat-panel monitors use liquid crystal display (LCD) technology;
There are two types of LCDs….
i. Passive matrix LCD:
Passive matrix LCD uses a transistor for each row & column of pixels;
ii. Active matrix LCD:
Active matrix LCD uses a transistor for each pixel on the screen;
Ø Thin-film transistor (TFT) displays use multiple transistors for each pixel.
8. Define pixel and resolution;
Ans. Pixel:
A pixel (or picture element) is the smallest item of information in an image. Pixels are normally arranged in a 2-dimensional grid, and are often represented using dots, squares, or rectangles. Each pixel is a sample of an original image, where more samples typically provide more-accurate representations of the original. The intensity of each pixel is variable; in color systems, each pixel has typically three or four components such as red, green, and blue, or cyan, magenta, yellow, and black.
Resolution:
The level of information on a display device is called resolution, such as a monitor; actually resolution is the number of pixels on the screen, expressed as a matrix (such as 600X480).
9. What is dot pitch and refresh rate?
Ans. Dot pitch:
Dot pitch is the distance between the phosphor dots that make up a single pixel; in color monitors, three dots (red, green & blue) comprise each pixel.
Refresh rate:
Refresh rate is the number of times each second that the electron guns scan the screen’s pixels; refresh rate is measured in Hertz (Hz), or cycles per second.
10. How can we evaluate a monitor?
Ans. We can evaluate a monitor by considering four features, these are….
i. Size;
ii. Resolution;
iii. Refresh rate;
iv. Dot pitch;
i. Size:
ü A monitor’s size is the diagonal measurement of its face, in inches;
ü For years, 15” monitors (13” viewing area) were standard;
ü Today, 17” monitors (15” viewing are) are common;
ü Larger monitors are available, but can be expensive.
ii. Resolution:
ü Resolution is the number of pixels on the screen, expressed as a matrix (such as 600X800);
ü A 17”monitor offers resolution from 640X480 up to 1280X1024;
ü The Video Graphics Array (VGA) standard is 640X480. Super VGA (SVGA) monitors provide resolution of 800X600, 1024X768 or higher.
iii. Refresh rate:
ü Refresh rate is the number of times each second that the electron guns scan the screen’s pixels;
ü Refresh rate is measured in Hertz (Hz), or cycles per second;
ü We should look for a refresh rate of 72 Hz or higher. A slower rate may cause eyestrain;
iv. Dot pitch:
ü Dot pitch is the distance between the phosphor dots that make up a single pixel;
ü In color monitors, three dots (red, green & blue) comprise each pixel;
ü We should look for a dot pitch no greater than .28 millimeter;
So from the above discussion we can say that, a monitor can be easily evaluated through considering these features.
11. Write the difference between impact & non-impact printer;
Ans. Difference between impact & non-impact printer:
| Impact printer | Non-impact printer |
| 1. Impact printer use a device to strike an inked ribbon, pressing ink from the ribbon onto the paper; 2. Impact printers are like typewriters they hit an inked tape to imprint the letters on the paper. 3. In impact printers the paper & the printer head come in contact and hence the text or image is formed. 4. Impact printers are noisily because of the hitting activity; 5. Impact printers are usually less expensive than non-impact printers; 6. Example - Dot Matrix printer, Daisy Wheel printer etc. | 1. Non-impact printers use different methods to place ink (or another substance) on the page; 2. Non Impact either are ink jet that sprays the ink on the paper or can be laser where you use a toner cartridge and a laser to imprint the paper. 3. In non-impact printers the text or image is formed without any physical contact of the paper and the printer head; 4. Non-impact printers are quieter & produce better quality print than impact printers; 5. Non-impact printers are usually more expensive than impact printers; 6. Example - Ink jet printer, Laser printer etc. |
12. List some impact & non-impact printer;
Ans. List of Impact printer: List of Non-impact printer
a. Dot matrix printer; a. Ink jet printer;
b. Daisy wheel printer; b. Laser printer;
c. Line printer; c. Laser jet printer;
d. Drum printer; d. Desk jet printer;
e. Line matrix printer: e. Thermal printer;
13. How does dot-matrix printer work?
Ans. Dot Matrix printers are a common type of impact printer;
Ø A dot matrix printers’ print head contains a cluster of pins. The printer can push the pins out to form patterns in rapid sequence;
Ø The pins press an inked ribbon against the paper, creating an image.
This is how dot-matrix printer works.
v The illustrator is in the lecture sheet, given by the teacher;
14. How does laser printer work?
Ans. Laser printers are non-impact printers. They are available for color & black and white printing.
Ø Laser printers use heat and pressure to bond particles of toner to paper;
This is how laser printers work.
v The illustrator is in the lecture sheet, given by the teacher;
15. How can we evaluate a printer?
Ans. We can evaluate a monitor by considering four features, which are….
i. Image quality:
Image quality measured in dots per inch (dpi). Most printers produce 300 – 600 dpi;
ii. Speed:
Speed measured in pages per minute (ppm) or characters per second (cps);
iii. Initial cost:
Consumer’s printers cost $250 or less, but professional printers can cost thousands of dollars;
iv. Cost of operation:
Cost of operation refers to the cost of supplies used by the printer;
16. Write the differences between primary storage & secondary storage;
Ans. Difference between primary storage & secondary storage:
| Primary storage | Secondary storage |
| 1. A primary storage device storage location that holds memory for short periods of times; 2. Most Primary Storage is temporary; 3. Primary Storage is expensive and smaller; 4. Primary storage is smaller in capacity (L2 Cache is only 2MB); 5. Primary storage is usually faster therefore more expensive; 6. Example - RAM ,L2 Cache etc. | 1. A secondary storage device on the other hand is a storage medium that holds information until it is deleted or overwritten; 2. All secondary storage is permanent; 3. Secondary storage is usually cheaper and large; 4. Secondary Storage is bigger in capacity; 5. Secondary storage connects to the CPU via cables and therefore is slower; 6. Example - Hard drive, CD-ROM etc. |
17. Write the functions of RAM and ROM BIOS;
Ans. Functions of RAM:
RAM stands for Random Access Memory. It’s temporarily storage memory. It’s the main memory of the operating system. It’s the most common computer memory which is used by programs to perform necessary tasks while the computer is on. An integrated circuit memory chip allows information to be stored or accessed in any order; and all storage locations are equally accessible.
Functions of ROM BIOS:
ROM is a "write once" memory. It’s mostly set as a security reason to prevent unauthorized user from changing the content. In other words, it is memory that cannot be rewritten. ROM generally comes in the form of IC chips which contain the basic functions to start/run a computer or the devices within it. The most visible form of ROM is the BIOS (think of that screen that shows up when we start our computer). When we start our computer, it accesses the BIOS which tell the CPU how to access the hard drive, video, and basic input devices. ROM will control devices that are not really dependant on updates like burglar alarms, clocks etc.
18. List different storage devices;
And. There are two types of primary storage technologies, which are….
i. Magnetic storage &
ii. Optical storage;
List of Primary types of Magnetic storage devices:
· Diskettes (floppy disks);
· Hard disks;
· High-capacity floppy disks;
· Disk cartridges;
· Magnetic tape;
List of Primary types of Optical storage devices:
· Compact Disk Read-Only Memory (CD-ROM);
· Digital Video Disk Read-Only Memory (DVD-ROM);
· CD-Recordable (CD-R);
· CD-Rewritable (CD-RW);
· Photo CD;
19. How does magnetic storage work?
Ans. How magnetic storage works:
ü A magnetic disk’s medium contains iron particles, which can be polarized – given a magnetic charge – in one of two directions;
ü Each particle’s direction represents a 1 (on) or 0 (off), representing each bit a data that the CPU can recognize;
ü A disk drive uses read/write heads containing electromagnets to create magnetic charges on the medium.
20. How does optical storage work?
Ans. How optical storage works:
ü An optical disk is a high - capacity storage medium. An optical drive uses reflected light to read data;
ü To store data, the disk’s metal surface is covered with tiny dents (pits) & flat spots (lands), which cause light to be reflected differently;
ü When an optical drive shines light into a pit, the light cannot be reflected back. This represents a bit value of 0 (off). A land reflects light back to its source, representing a bit value of 1 (on).
21. Why do we need formatting?
Ans. Before a magnetic disk can be used, it must be formatted;
Why we need formatting:
ü Formatting is a process that maps the disk’s surface & determines how data will be stored;
ü During formatting, the drive creates circular tracks around the disk’s surface, then divides each track into sectors;
ü The OS organizes sectors into groups, called clusters, and then tracks each file’s location according to the clusters it occupies.
22. Define track, sector, cluster & cylinder;
Ans. Track:
A track is the circular portion of the disk surface that passes under the read/write head as the disk rotates;
Sector:
Each track is divided into sectors that hold a fixed number of bytes. Data on the track is accessed by referring to the surface number, track number, and sector number where the data is stored.
Cluster:
A cluster is a fixed number of adjacent sectors that are treated as a unit of storage by the operating system; it consists of two to eight sectors, depending on the operating system.
Cylinder:
On a hard disk that has multiple platters, a cylinder consists of the track on each surface that is beneath the read/write head at a given position of the read/write arms.
23. Describe different types of RAM;
Ans. Different types of RAMs are described below….
DRAM:
Dynamic random access memory (DRAM) is a type of random access memory that stores each bit of data in a separate capacitor within an integrated circuit. Since real capacitors leak charge, the information eventually fades unless the capacitor charge is refreshed periodically. Because of this refresh requirement, it is a dynamic memory as opposed to SRAM and other static memory.
The advantage of DRAM is its structural simplicity: only one transistor and a capacitor are required per bit, compared to four transistors in SRAM. This allows DRAM to reach very high density. Unlike flash memory, it is volatile memory (cf. non-volatile memory), since it loses its data when the power supply is removed.
SRAM:
Static Random Access Memory (SRAM) is a type of semiconductor memory where the word static indicates that, unlike dynamic RAM (DRAM), it does not need to be periodically refreshed, as SRAM uses bitable latching circuitry to store each bit. SRAM exhibits data reminiscence, but is still volatile in the conventional sense that data is eventually lost when the memory is not powered.
DDR SDRAM:
DDR SDRAM (double-data-rate synchronous dynamic random access memory) is a class of memory integrated circuits used in computers. It achieves nearly twice the bandwidth of the preceding "single data rate" SDRAM by double pumping (transferring data on the rising and falling edges of the clock signal) without increasing the clock frequency.
With data being transferred 64 bits at a time, DDR SDRAM gives a transfer rate of (memory bus clock rate) × 2 (for dual rate) × 64 (number of bits transferred) / 8 (number of bits/byte). Thus with a bus frequency of 100 MHz, DDR SDRAM gives a maximum transfer rate of 1600 MB/s.
DDR2 SDRAM:
DDR2 SDRAM is a double data rate synchronous dynamic random access memory interface. It supersedes the original DDR SDRAM specification and the two are not compatible. The primary improvement that DDR2 brings over its predecessor is the operation of the external data bus at twice the clock rate. This is achieved by operating the memory cells at half the clock rate (one quarter of the data transfer rate), rather than at the clock rate as in the original DDR. Consequently, DDR2 memory operates at the same external data bus clock rate as DDR will provide the same bandwidth but with higher latency, resulting in inferior performance. Alternatively, DDR2 memory operating at twice the external data bus clock rate as DDR may provide twice the bandwidth with the same latency (in nanoseconds).
DDR3 SDRAM:
In electronic engineering, DDR3 SDRAM or double-data-rate three synchronous dynamic random access memory is a random access memory interface technology used for high bandwidth storage of the working data of a computer or other digital electronic devices. DDR3 is part of the SDRAM family of technologies and is one of the many DRAM (dynamic random access memory) implementations.
DDR3 SDRAM is an improvement over its predecessor, DDR2 SDRAM. The primary benefit of DDR3 is the ability to transfer twice the data rate of DDR2 (I/O at 8× the data rate of the memory cells it contains), thus enabling higher bus rates and higher peak rates than earlier memory technologies.
Z-RAM:
Z-RAM, short for "zero capacitor RAM" is a new type of DRAM computer memory in development by Innovative Silicon based on the floating body effect of silicon on insulator (SOI) process technology. Z-RAM has been licensed by Advanced Micro Devices for possible use in future microprocessors. Z-RAM offers memory access speeds similar to the standard six-transistor SRAM cell used in cache memory but uses only a single transistor, therefore affording much higher packing densities.
TTRAM:
TTRAM is similar to conventional one-transistor, one-capacitor DRAM in concept, but eliminates the capacitor by relying on the floating body effect inherent in a silicon on insulator (SOI) manufacturing process. This effect causes capacitance to build up between the transistors and the underlying substrate, originally considered a nuisance, but here used to replace a part outright. Since a transistor created using the SOI process is somewhat smaller than a capacitor, TTRAM offers somewhat higher densities than conventional DRAM.
MRAM:
Magneto resistive Random Access Memory is a non-volatile computer memory (NVRAM) technology, which has been under development since the 1990s. Continued increases in density of existing memory technologies – notably Flash RAM and DRAM – kept it in a niche role in the market, but its proponents believe that the advantages are so overwhelming that Magneto resistive RAM will eventually become dominant for all types of memory, becoming a true universal memory.
PRAM:
Phase-change memory (also known as PCM, PRAM, PCRAM, Chalcogenide RAM and C-RAM) is a type of non-volatile computer memory. PRAM uses the unique behavior of chalcogenide glass, which can be "switched" between two states, crystalline and amorphous, with the application of heat. Recent versions can achieve two additional distinct states, effectively doubling its storage capacity. PRAM is one of a number of new memory technologies that are attempting to compete in the non-volatile role with the almost universal Flash memory, which has a number of practical problems these replacements hope to address.
NRAM:
Nano-RAM is a proprietary computer memory technology from the company Nantero. It is a type of nonvolatile random access memory based on the mechanical position of carbon nanotubes deposited on a chip-like substrate. In theory the small size of the nanotubes allows for very high density memories. Nantero also refers to it as NRAM in short.
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