Basics of Computers Long Answer Type Questions Part 3
Discuss in brief about key board and mouse.
Keyboard: A computer keyboard is one of the primary input devices used with a computer that looks similar to those found on electric typewriters, but with some additional keys. Keyboards allow you to input letters, numbers, and other symbols into a computer that can serve as commands or be used to type text.
The standard selection of keys can be classified as follows:
- Alphanumeric keys: The standard letters and numbers.
- Punctuation keys: The comma, period, semicolon, and similar keys.
- Special keys: This includes the function keys, control keys, arrow keys, caps Lock key, and so on.
A mouse is a small handheld input device that controls a computer screen’s cursor or pointer in conjunction with the way it is moved on a flat surface. The mouse term name originates from its likeness to a small, corded and elliptical shaped device that looks like a mouse tail. Some mouse devices have integrated features, such as extra buttons that may be programmed and assigned with different commands.
Because the mouse reduces the use of a keyboard, its invention and continuous innovation is considered one of the most important breakthroughs in computer ergonomics.
The mouse was invented in 1963 by Douglas C. Engelbart from Stanford and later pioneered in 1981 by the Xerox Corporation. Computer users were generally skeptical about the mouse invention until approximately 1984, when the original Apple Macintosh (Macintosh 128K) was released.
Early mouse devices connected to computers through a cable or cord and were characterized by a roller ball integrated as a movement sensor underneath the device. Modem mouse devices use optical technology, where cursor movements are controlled by a visible or invisible light beam. Many models feature wireless connectivity through various wireless technologies, including radio frequency (RF) and Bluetooth.
The three main mouse device types are:
- Mechanical: Built with a trackball underneath the mouse and mechanical sensors, allowing easy movement in all directions
- Optomechanical: Similar to the mechanical type but uses optical, rather than mechanical, sensors to detect trackball movement
- Optical: The most expensive. Uses a laser to detect mouse movement, has no mechanical parts and reacts more precisely than other types.
There are four basic mouse operations that you can perform:
1. Click: To select an item or choose a menu command, point the mouse at it with the pointer and the left mouse button.
2. Click and Drag: To move an item is called dragging. To complete this operation, point at the item, it and hold down the left mouse button. While holding down the left mouse button drag the item where you want it to be. Release the button.
3. Double-Click: This is a shortcut method used to access an item or to open or close a window quickly without using a menu. To complete this operation, point the mouse pointer to the item and it with the left mouse button.
4. Right-Click: When you click the right mouse button you can access a drop down menu to choose what you can do with the item, such as “copy, “paste”, etc. Every menu is specific to what you click. To perform this operation, point at the desired item or object and the right mouse button ONLY once.
Write a short notes on Printers?
Generally, printers fall into- two categories : a) Impact Printers and b) Non-Impact Printers.
An impact printer creates an image by using pins or hammers to press an inked ribbon against the paper. The most common type of impact printers is the dot matrix printer Line printers, and band printer. Non-impact Printers use other means to create an image. Examples for the non-impact printers are Ink jet printers, and laser printer
Dot Matrix Printers: A dot matrix printer creates an image by using a mechanism called a print head, which contains a matrix of short pins arranged in one or more columns. On receiving instruction from the PC, the printer can push any of the pins out in any combination. By pushing out pins in various combinations, the print head can create alphanumeric characters which is show in the following figure.
The speed of dot matrix printers is measured in characters per second (CPS). The slowest dot matrix printer create 50 to 70 characters per second; the fastest print more than 500 cps. The following figure shows
Line Printers: A line printer is a special type of impact printer. It works like dot matrix printer but uses a special wide print head that can print an entire line of text at one time. Line printers do not offer high resolution but are incredibly fast; the fastest can print 3,000 lines of text per minute.
Band Printers: A band printer features a rotating band embossed with alphanumeric characters. To print a character, the machine rotates the band to the desired character, then a small hammer taps the band, pressing the character against a ribbon. A good-quality band printer can generate 2,000 lines of text per minute.
Ink Jet Printers : Ink jet printers create an image directly on the paper by spraying ink through tiny nozzles. The ink jet printers can print two to four pages per minute. Many ink jet printers use one cartridge for color printing and a separate black- only cartridge for black-and-white printing. This feature saves money by reserving colored ink only for color printing.
Laser Printers: Laser printers are more expensive than ink jet printers, their print quality is higher, and most are faster. As their name implies, a laser is at the heart of these printers. Just as the electron gun in a monitor can target any pixel, the laser in a laser printer can aim at any point on a drum, creating an electrical charged. Then with pressure and heat, the toner is transferred off the drum onto the paper.
A color laser printer works like a single color model, except that the process is repeated four times and a different toner color is used for each pass. The four colors used are Cyan, Magenta, Yellow and Black.
Plotters: A plotter is a special kind of output device, ft is like a printer because it produces images on paper, but the plotter is typically used to print large-format images, such as construction drawings created by an architect.
Discuss about Plotters.
A plotter is a printing device that is usually used to print vector graphics with high print quality. They are widely used to draw maps, in scientific applications, and in CAD, CAM, and computer aided engineering (CAE). Architects use plotters to draw blueprints of the structures they are working on. A plotter is basically a printer that interprets commands from a computer to make line drawings on paper with one or more automated pens. Since plotters are much more expensive than printers, they are used only for specialized applications. Hewlett-Packard is the leading vendor of plotters worldwide. There are two different types of plotters, drum and flatbed.
Drum plotter: A drum plotter is used to draw graphics on paper that is wrapped around a drum. This type of plotter is usually used with mainframe and minicomputer systems. The drum plotter works by rotating the drum back and forth to pro-duce vertical motion. The pen, which is mounted on a carriage, is moved across the width of the paper. Hence, the vertical movement of the paper and the horizontal movement of the pen create the required design under the control of the computer.
Drum plotters can make multicolour drawings by using pens with different coloured inks. Moreover, drum plotters support very large plot sizes with paper widths of up to 1 metre.
Flatbed plotter: In a flatbed plotter, the paper is spread on the flat rectangular surface of the plotter, and the pen is moved over it. Flatbed plotters are less expensive, and are used in many small computing systems. The size of the plot is limited only by the size of the plotter’s bed. In this type of plotter, the paFcr does not move; rather, plotting is done by moving an arm that moves a pen over the paper.
In case of a flatbed plotter, pens of different colours are mounted in the pen-holding mechanism that moves on the sur-face. The microprocessor in the plotter selects the desk pen and controls its movement under the control of the computer.
What is Software? Explain different types of Software?
Answer: The Computer is a machine and it can not think and do its own. Since it has no intelligent quotient, it must be instructed to carry out any task. Hence it is required to specify the set of sequential instructions that the computer can perform to solve any task.
Software is basically “the set of instructions grouped into programs that make the computer to function in the desired way. It is a collection of programs to perform a particular task.
A system software is a collection of programs designed to operate, control and extend processing capabilities of computer and which makes the operation of a computer system more effective and efficient. The system software can be divided into two types
a) Operating System
b) Language Translators/Processors
a) Operating System: An operating system plays an important role in a computer system which controls all other components of the computer system. If there is no operating system, then there is no computer. It controls the CPU, Memory, Input / Output devices etc. It is responsible for smooth functioning and efficient operation of the computer system. Some of the popular operating system are DOS, WINDOWS, UNIX and LINUX etc.
b) Language Translators/Processors: A programmer can write program in high level language because it is much easy to understand by the computer and convert into its own machine language. Language Translators converts the high level language program into machine understandable form (Machine language). The language processors are Assembler, Interpreter, Compiler.
Application software is a set of programs necessary to carryout operations for a specific application. These are the programs written by programers to enable computer to perform a specific task. Application software can be divided into two categories.
a) Special purpose Application Software
b) General Purpose Application Software
a) Special Purpose Application Software: This is based upon the customer requirements. This is developed to meet all the requirements mentioned by the customer. This requirement cannot be directly installed to any other user’s workspace, because requirement may differ from one customer to another customer so this software may not fulfil to everyone.
b) General Purpose Application Software: This type of software developed for general requirements for carrying out a specific task. Here many customers can use simultaneously due to filfilment of all customers.
What is Hardware and Software and differentiate them.
The term hardware is applied to any of the physical equipments in the computer system, such as the machinery and equipments of itself usually containing electronic components and performing some kinds of functions in information processing. Thus the input, output, storage, processing and control devices are the hardware of the computer system. On other hand, the set of instrucitons grouped into programs that make the computer to function in the desired way. Collection of programs to perform a particular tasks is called software.
- It is the collection of programs to perform a particular task.
- There are so many different types of softwares available for different purposes.
- The softwares are categorized as system softwares and application softwares.
- Without the software, we can not do any task using the computer.
- Sufficient training is necessary to use the software.
- Software is continuing expenses.
- It is formed as the physical components of the computer system.
- All of the hardware parts may do different tasks such as Hard disk is for storing, Keyboard is for giving inputs etc.,
- The hardware peripherals are also categorized such as 12GHz Microprocessors, 2GHz Microprocessors and so on,
- Without the hardware, there is no computers.
- Sufficient training is necessary to use the hardware.
- Except for upgrading, it is one-time expense.
Differences between the software and hardware:
|1. It is collection of program to bring the computer hardware system into operation.||It is the physical components of the computer system.|
|2. It consists of numbers, alphabets, alphanumeric symbols, identifiers, keywords, etc.||It consists of electronic components like IC’s diodes, resistors, crystals boards, insulators etc.|
|3. This should be prepared according to the type of the software.||The design can be modified according to the capacity.|
|4. It will vary as per the computer and its built-in function and programming language.||It is almost construct for all types of computer system.|
|5. It is designed and developed by a experienced programmer in a high level language, which is readable by the human being.||The hardware can understand only low- level language or machine language.|
|6. It is represented in any high level language such as BASIC, COBOL, C, C++, JAVA etc.||The hardware works only on binary code as 1’s and 0’s.|
|7. The software is categorized as operating systems, utilities, language processors, application software etc.||The hardware consists of Input, Output, Memory, ALU, Control Unit etc.|
Define Memory? Discuss about Main Memories in detail?
The function of the memory is to store data or programs or information are in the form of “ON” and “OFF” States. Because Computer is an electronic device which identified only two signals either “ON” and “OFF” states. That’s why all the information or data or programs are stored inside the computer are in the form of “ON” and “OFF” states. Memories further divided into two types they are a) Primary Memories and b) Secondary Memories.
a) Primary Memories: The primary memory of computer is called as main memory. The main memories are fast memories. It is used to store programs and data. The memory location of main memory is accessed directly by the CPU. Main memory uses semi-conductor technology. These memories are very costlier. It has random access property and small access time. The capacity of primary memory is limited. Each storage locations has unique address by which it can be identified. The following primary memories are commonly used in computers, (a) Magnetic Core Memory and (b) Semi-conductor Memory.
b) Magnetic Core Memory: Magnetic core memory made up of small magnetic cores with wires running through them. Depending on the direction of the electric current flows through the wires, electricity magnetizes the core in different directions. The direction of magnetization indicates certain data representation of the CPU., Since the form f memory is bulky., it lias given way to newer technologies such as semiconductor memories.
b) Semi-conductor Memory : The modem computers are made up of semi-conductor elements in the primary storage units. This type of memory is made by etching electronic circuits onto a silicon chip.
In all computers semi-conductors are used for Primary memory storage. It is divided into two portions, (i) ROM (Read Only Memory) (ii) RAM (Random Access Memory).
ROM Memory: ROM is an acronym for Read-Only Memory. It refers to computer memory chips containing permanent or semi-permanent data. Unlike RAM, ROM is non-volatile; even after you turn off your computer, the contents of ROM will remain.
Almost every computer comes with a small amount of’ ROM containing the boot firmware. This consists of a few kilobytes of code that tell the computer what to do when it starts up, e.g., running hardware diagnostics and loading the operating system into RAM. On a PC, the boot firmware is called the BIOS.
Originally, ROM was actually read-only. To update the programs in ROM, you had to remove and physically replace your ROM chips. Contemporary versions of ROM allow some limited rewriting, so you can usually upgrade firmware such as the BIOS by using installation software. Rewritable ROM chips include PROMs (programmable read-only memory), EPROMs (erasable read-only memory), EEPROMs (electrically erasable programmable read-only memory), and a common variation of EEPROMs called flash memory.
RAM Memory: Random Access Memory (RAM) provides space for your computer to read and write data to be accessed by the CPU (central processing unit). When people refer to a computer’s memory, they usually mean its RAM.
If you add more RAM to your computer, you reduce the number of times your CPU must read data from your hard disk. This usually allows your computer to work considerably faster, as RAM is many times faster than a hard disk.
RAM is volatile, so data stored in RAM stays there only as long as your computer is running. As soon as you turn the computer off, the data stored in RAM disappears.
When you turn your computer on again, your computer’s boot firmware (called BIOS on a PC) uses instructions stored semi-permanently in ROM chips to read your operating system and related files from the disk and load them back into RAM.
SDR, DDR, DDR2, and DDR3 RAM: Several types of. RAM are used in modern computers. Before 2002, most computers used single data rate (SDR) RAM. Most computers made since then use either double data rate (DDR), DDR2, or DDR3 RAM. DDR2 is able to achieve faster transfer rates to prevent limitation of your CPU’s performance, and DDR3 technology takes these advancements even further.
What is Cache Memory? Explain
Cache memory is an intermediate form of storage between the CPU registers and the RAM. The CPU uses cache memory to store instructions and data that are repeatedly required to execute programs, thereby increasing the performance of the computer.
Maintaining frequently accessed data and instructions in the cache helps in avoiding the need to access the slower DRAM repeatedly. Cache memory is basically a portion of memory made of high speed static RAM (SRAM) instead of the slower and cheaper DRAM which is used for main memory. Some memory caches are in-built in the architecture of microprocessors. For example, the Intel 80486 microprocessor has an 8K memory cache, and the Pentium has a 16K cache. Such internal caches are often called level 1 (LI) caches.
Modem PCs also come with external cache memory, called level 2 (L2) caches, which are built into the motherboard outside the CPU. Although L2 caches are composed of SRAM, they are much larger in size than LI caches. Another type of cache, called level 3 (L3).
When a program is being executed and the CPU wants to read data or instructions, the following steps are performed.
- The CPU first checks whether the data or instruction is , available in the cache memory.
- If it is not present there, the CPU reads the data or instructions from the main memory into the processor registers and also copies it into the cache memory.
- When the same piece of data/instruction is needed again, the CPU reads it from-the cache memory instead of the main memory.
Discuss about Secondary Memories in detail.
When the computer is switched off, anything stored in the RAM is lost. To avoid this situation, magnetic disks are used to store data permanently. The data, on these disks, won’t be affected when we turn off our computer.
a) Floppy Disk:
A floppy disk is a reusable data storage device that is composed of a disk of thin, flexible (“floppy”) magnetic storage medium encased in a square or rectangular plastic shell. Also called a “diskette,” the floppy is a flexible circle of magnetic material similar to magnetic tape, except that both sides are used. The read/write head contacts the surface through an opening in the plastic shell or envelope. Floppies rotate at 300 RPM, which is from 10 to 30 times slower than a hard disk. Floppy disks basically come in three sizes, they are 8 inches, 5 ¼ inch, and 3 ½ inch.
b) Hard Disk:
A hard disk, is also a permanent storage, where we can store lot of information. Capacity of a hard disk is measured in Megabytes (MB), Gigabytes(GB) or Terabytes(TB) and they come in various different sizes. Usually every computer now a days comes with hard disk.
The information in hard disk is stored in circular magnetic disks called plates, in the form of program files and data files.
c) CD-ROM (Compact Disk – Read Only Memory):
CD-ROM is also one of the commonly used secondary storage device. The main advantage of CD-ROM is, they can store large volumes of data i.e., 700 MB to 1.4 GB and also they are cheaper and easy to handle. It is made up of small plastic disk, coated with aluminum or silver for magnetization. A layer or transparent plastic is further deposited on the disk. The data is recorded in spiral tracks and the data once recorded cannot be deleted or rewritten, but can be read any number of times.
In this technology, a high power laser beam is used to record data by burning tiny pits in the surface of the hard plastic disk. To read the data, a low power laser beam is used to scan the disk surface. The data are stored in binary digits. When the laser beam reflects from the smooth surface of the disk it is interpreted as a 1 bit and when the beam enters the tiny pits it is interpreted as a 0 bit.
- High Storage Capacity
- Easy to use in multimedia applications.
- Handled easily.
- Can read/Rewrite using CD-RW’s
- CD Writing can be done carefully
- Should be kept free from dust and heat.
d) Magnetic Tape:
Magnetic tape is the oldest form of secondary storage device. It is one of the popular storage medium for storing large amount of sequential data. It is also used as a backup storage for data stored on on-line storage devices.
The magnetic tape medium is a plastic ribbon usually 1/2 inch or 1/4 inch wide and 50 to 2400 feet long. It is coated with a magnetizable recording material such as iron-oxide or chromium dioxide. Data are recorded on the tape in the form of ^ tiny invisible magnetized and non-magnetized spots on the coated surface of the tape.
- Non-volatile Memory
- Voluminous data can be stored.
- Only sequential data processing
- Complex mechanism required.
- After few days the data can be mounted to tape, we need to recall the data to store it into hard disk as and when required.