Thursday, July 22, 2010

Can I sign up for more than one account?




Advantages and Disadvantages of Computers


Computer has many pros and cons, as every object in this world has. It's advantages and disadvantages are listed below:
Advantages
a) Computers are 100% accurate and much more reliable than any other devices and human beings.
b) Computer is much faster than human
c) It is very much useful for repeated jobs, which is difficult and tedious for human to do.
d) With the help of computer, impossible things are easy to show and simulate.
e) It is versatile and can perform various types of works.
f) It can be used in multiple fields so it is called general purpose machine.
g) Because of the availability of storage, programs can be modified to add features for different purpose.
Disadvantages
a) It is expensive and is beyond the reach of poor people. This limitation is being overcome because its cost is drastically decreasing day by day.
b) It is electronic machine, so there is much danger of electric shock and other physical damages.
c) Since it is much reliable, sometimes the failure in devices and programs can produce unreliable information and cause loss of data in a great extend.
d) It increases dependency on machine. Even for very simple calculation people need them.
e) Although it helps in faster and cheaper communication, there is much danger of security leakage by third party by which authentication becomes questionable.
f) In underdeveloped countries like Nepal, it increases piracy of intellection properties in big volume.
g) Since computers are used in sensitive areas like natural defense, civil aviation, banking, so even a simple mistake can cause loss of life and property.

Batch systems


A batch system is one in which jobs are bundles together with the instructions necessary to allow them to be proposed without user intervention.
The simple operating system also called monitor is system software responsible for interpreting and carrying out the instructions in the batch jobs. When the monitor started a job, it is finished. Such batch system is called stacked job or simple batch system.
Often magnetic tapes and drums were used to store intermediate data and compiled programs.
1. Advantages of batch systems
Ø Move much of the work of the operator to the computer
Ø Increased performance since it was possible for job to start as soon as the previous job finished
2. Disadvantages
Ø Execution time can be large from user's point of view.
Ø Due to lack of protection scheme, one batch job can affect pending jobs
Ø A job could corrupt the operating system thus may affect pending jobs
One difficulty with simple batch simple batch systems is that the computer still needs to read the deck of cards before it can begin to execute the job. This means that the CPU is idle (or nearly so) during these relatively slow operations.
Capabilities and Limitations of Computer
Computer is a device, which is capable of doing almost all the works, which can be programmed by the user. But there are some functions, which are impossible for a computer to perform. Following are some of the capabilities and limitations of computer:
Capabilities
(a) Computers can do jobs with 100% accuracy and in a very fast speed in comparison to any other devices or human.
(b) It is possible to show and do the things, which are impossible for humans.
(c) Computer provides faster and cheaper communication with the use of various commutation technologies.
(d) it can perform almost all the works but for any purpose, user must provide proper program and necessary hardware.
Limitations
(a) Computer is a dull machine. It doesn't have intelligence on it. So, whatever it does, that is with the help of programs and devices developed by human. If such assistances are not provided, it will not be able to perform the simple of the simplest works, too. If any error occurs in its structure or circuitry, then the output (result) given by it is wrong which is very hard to tackle . It can't distinguish between the good and bad inputs and outputs in comparing to human. So, it is often called 'idiot servant'.

Analog computer


The Computers, which work with the natural phenomena and physical values like frequency, earthquake, volcano, water flow, current flow etc, are known as analog computers. They are based on continuous changing values or voltage levels. These types of computers are used in scientific work, commercial and personal purpose. Examples of analog computer some of its characteristics are presented below:
1. Based on continuous varying data.
2. Measure only natural or physical values.
3. Used for special purpose.
4. Generally, no storage facility is available because they work on
real time basis. If provided, then only a little amount of storage
is available in it.
5. Accuracy of these types of computers is very less because of
noise and Filtering facility. Increasing accuracy is costly.
6. Output of that signal sis also not well known by general public
because They are in form of wave lines, curved lines or grapes.
7. The wave form of analog signals is represented in figure below.

1.1o.2.2 Digital Computer: - These computers are based on discrete quantities and are represented with binary numbers. They are based on binary digits. Binary system is such system of numbering in which only 2 digits are used 0 and 1. Meaning of 0 is either OFF; FALSE, NO etc and 1 is ON, TRUE, YES etc. So the basic principle of these computers is either present or absence of electrical pulses in the signals, Examples of these computers are IBM PC, Apple/Macintosh etc. Some major characteristics of these computers are listed below:
1. Based on discrete data which are not continuous with time.
2. Based on principle of logic 1 and 0 (high and low voltage).
3. Used for general purpose.
4. They are more reliable because of less noise and filtering facility.
5. It has large memory capacity because the calculations are to be stored
internally for future use and re-programming.
6. It is multipurpose and programmable, so, it is of high cost and faster
Processing.
1. Signal representation of digital pulses is shown in figure below.

1.10.2.3 Hybrid Computers
Hybrid means combination or cross-link of two or more types. So, as the name suggests, it is combination of analog and digital computers. It can perform the works done by analog computers as well as digital computers, examples of these types of computers are: computers used in hospitals, computers used in jet planes etc. The best example of hybrid device is Modern. It consists of both analog and digital parts. Some other major characteristics of these computers are presented below.
1. Combination of good qualities of analog as well as digital computer.
2. Can process both continuous and discrete data. It has capacity to convert one type of data into another.
3. These are special purpose machine.
4. Mostly used in airplanes, hospitals etc.
5. High cost.

c) On the basis of brand
- IBM Computer
IBM, which was established by Dr. Herman Holleith in 1923 AD, is the largest computer manufacturing company in the world till today. It was leading the market of mainframe and PCs. Nowadays it uses the processors, multimedia devices and some other hardware parts developed by some other companies like Intel but use the principle of its own. So, all the computers developed by IBM company are called IBM computers, it has two categories; a) IBM PC and b) IBM compatible. The computers developed by IBM company itself are called branded or IBM PC. Computers which are developed or assembled by other companies using the parts and principle of IBM PCs are called IBM compatibles. So, IBM compatibles are also called duplicate of IBM PCs.

- Apple/Macintosh Computer: - Apple Corporation was established in 1970 AD in USA. By far it has gone much forward and produced PCs with good qualities and user friendly. So, all the computers that are developed by Apple Corporation are called Apple/ Macintosh (Mac) computers. These computers are architecturally totally different. Software made of IBM's not only hardware part, but their software architecture is also totally different. Software made for IBM PC can't be run in Macintosh or vice versa. Floppy disks or hard disks formatted in one can't be recognized by other. Before 2006 they used power PC processor like G3, but nowadays they are using Intel processor.

d) On the basis of model
- XT Computer: - XT (eXtra Technology) Computers are the old technology computers with much slower processing speed (not more than 4.77 Mhz). Advanced GUI based software like (Windows) can't be run in these computers. Everything was based on text based system. Serial number of processors was like 8086, 8088 which were developed bye Intel and were 16 bit world length. Complex calculation and large processing couldn't be done. I/O devices were not flexible and faster.

- AT Computer: - AT (Advanced Technology) computers are the new technology computers. They are faster in processing than XT and can run any type of software whether that is text based or GUI based. Serial number of processors is 80286, 80386, 80486, Pentium1, Pentium 2 etc. Any type of complex and long processing can be done depending on the capacity of the computers. I/O devices are interactive, flexible and faster. Word length exceeds 16 bits. Co-processors are used to help the main processors for complex mathematics.

- PS/2 Computer: - Actually, these are not totally different models of computers but are refinement of AT computers. These models were built after 1990s and mostly used in laptop computers. Rechargeable and battery operated systems with faster and flexible I/O devices are some important characteristics of these computers. OS/2 operating system was used at the beginning but now-a-days, windows operating system is leading.
e) On the basis of purpose
- General purpose Computers: - The computers that can be used for verities of purpose are called general purpose computers. The general purpose computers can be used for word processing, spread sheet applications, multimedia applications, publications etc. The desktop computers are considered as the general purpose computers because they can be used for verities of applications.

- Specific purpose Computer: - The Computers that are used for some specific applications are called specific computers. The computers that are used to control the traffic light, the single chip computers used in automatic systems such as microwave oven, television set, automatic air conditioning systems and many other automatic systems are specific purpose computers. They are called specific purpose computer because they are used for one or some limited purpose.
i) George Boole: One of the greatest achievements of 19th century was the discovery of mathematical logics called 'Boolean Algebra'. He studied and presented the symbolic logics which are the foundation of modern computers. His logics provided basic idea of presenting the electric circuits with binary inputs (0 or 1) and its output.
(J) Dr. Herman Hollerith: He was a census statistician in Us bureau of statistics. He is remembered in the history of computers for the following contributions:
Operating system
Definition
The operating system is defined as set of programs that control the entire operation of the computer such as handling inputs/Output operation, user request, interrupts etc the operating system manages the resources of a computer system and schedules its operation. It is a master supervisory program which provides a friendly interface for the user to interact with the computer and its peripherals and different application software as well as an environment for program to execute.
Types of operating systems
Based on the technological development operating system can be divided as follows:

Types of Computers

Computers can be classified according to size, work, brand or model. so, if anybody asked which/what computer do you have ? A single answer is not sufficient. A single computer can be micro on the basis of size, IBM compatible on the basis of brand, AT on the basis of model and digital on the basis of work. Generally. we can classify computers on the following terms.
a) On the basis of size
On the basis of size computers can be classified into three groups. They are:
- Micro Computer
- Mini Computer
- Mainframe Computer
- Super Computer
Explanation of each is given below:
Micro computers
These are the smallest computer systems on the basis of size. These computers are called micro because microprocessor id used as CPU and they are very small. The smallest of this category are laptop, notebook and palmtop computers. The size is reducing day-by-day. Examples of this category are: IBM Pentium PC, Apple/Macintosh, Sun spark workstation etc. Some major characteristics of this category are as follows:
1. Smallest in terms of size. Can be kept on top of a desk (Desktop), on palm (palmtop), on top of our lap (laptop) and like a notebook.
2. Speed is highest and colt lower.
3. Since a single user system is used, storage devices and memory are smaller sized.
Mini computer
There are the medium sized computers on the basis of size. A centrally located CPU is connected with around 50 terminals. Examples of these computers are: Prime 9755, Vax36 etc. Some other major characteristics of this type of computers are listed below:
1. Medium sized computer occupying approximately 10 sq of area.
2. Around 50 terminals and large capacity storage devices than micro computers but smaller than mainframes.
3. Used for general purpose.
4. Used in medium sized organizations and corporations.
Mainframe computer
These are the largest computers on the basis of size. A centrally located CPU is connected with more than100 terminals. Examples of these computers are: IBM 1401, ICL 2950/10 etc. Some of the major characteristics of these computers are listed below:
1. Very large in size with approximately 1000sq. feet area.
2. Central processor, central administration.
3. More than 100 terminals, large capacity storage devices used.
4. Fastest and most expensive system in comparison to contemporary machines.
5. General purpose computers.
6. Used by large organization and governments for large scale data processing.
Super computer
Supercomputer is a computer that can process a great deal of information or make involved in extensive calculation very quickly. It processes the data instructions in millionths of a second, or microseconds. Supercomputers can resolve complex mathematical equations in a few hours, which would have taken a scientist with paper and pencil a lifetime, or years using a hand calculator.
b) On the basis of work
On the basis of the data they operate on computers can be classified as follows:
- Analog Computer
- Digital Computer- Hybrid Computer

History of Computer

The Computer was developed from the development of Abacus which was developed 3000 thousand year ago in China. It is one type of counting device which has two sections Heaven and Earth. By moving (Manipulating) the beds of heaven and Earth the counting works will be performed.
After the development of this device in different time period different types of advanced devices were developed. Such as; Napier's bone
Slide rule
Pascaline
The Computer is also developed by using these steps.
In 1946
According to this development of devices into different time period the computer can be categorized into different generation. They are ;
1. First Generation (1946-1958) :- In this time period the computer was developed for the first time. In this time period the memory devices was used in Computers. Which is known as vacume tube?

Features of Generation Computer
- It was very big in Size.
- It uses vacume tube as main memory.
- In this generation of Computer required more electricity (Power) up to 30 KB.
- It was very slow in processing.
- It generates more heat.
2. Second Generation (1958-1964) :- The development of Computer between the time period 1959 to 1964 is known as second Generation. In this generation the technology was developed than first generation.

Features of generation Computer
- It was transistor as main memory
- The size of computer was reduced than first generation
- It has high processing speed than previous generation
- It required less electricity than first generation.

3. Third Generation (1965-1974)
The development of Computer in this times period it known as third generation computer. In this time period the computer was more advanced and reliable.
Features of third generation
- IC was use as main memory and circuit.
- The size was also reduced then previous generation
- The processing speed was increased and memory capacity was also increased.
- It uses less electricity power than previous generation.
- All types of normal software can be easily run in this computer. So it provides friendly environment to the user.

Fourth generation computer (1975- Till)
The computer which we can use now days is known as fourth generation of computer. It has high processing speed and more storage capacity. It also can be categorized in different such categorized such as; Pentium one; Pentium 2 , 3 and 4.

Features of Forth generation
- VLSI and VVLSI were used as main chip.
-Processing speed was developed up to GHZ
- It has more storage capacity than pervious generation
- The storage capacity it up to GB.
- The size of this generation computer is decreased up to laptop computer.
- Ti required low electric power up to twelve volt.
Fifth generation of computer (not started)The fifth generation of computer has been expected self thinking capacity and understood the human language. The Biochips are used as main components of computer.

2. Out Put device

Input Device of Computer
1. Keyboard: It is known as primary input device. It is also known as typing device, because we can input the data and instruction by typing. It have different types of key combination such as, alphabetical keys (A to Z), numerical keys (0 to9), Function keys (F1 to F12) Arrow keys (Right, Left, Down and up) and other keys, Most of the keyboard have QWERTY layout; The keyboard have 102 to 108 keys and in FCC standard
2. Mouse: - It is other types of input device and also known as pointing device. By using the mouse pointer we can perform the works at computer. When we move the mouse the pointer will move to the same direction and when we click in certain command field the work mentioned at the command field will be performed. The mouse has to buttons (left and right). The left button is used for normal work and right button is used for other works. The stroller of mouse is used to move the working file up a down. The mouse is of three types they are Serial Mouse, Ps/2 Mouse and USB Mouse.
3. Scanner: - It is also another type of input device of computer. Especially this device is used to convert the hand copy data into soft copy and send the data to the computer. Basically used to input the picture files to the computer.
4. Digital Camera: - We can use this device to input the digital picture files to the computer we can connect the digital camera at computer by suing the USB port.
5. Joystick: - It is one type of control device, which is used for gaming option. This device is specially designed to play game at computer.
6. Light pen: - It has the light sensitive detector at its tip and it generates the light we should use this device at the pad, when we write something at pad the hand writing will input to the computer also it as known as input device.

2. Out Put device

Monitor: It is primary output device of computer and also known as VDU (Visual Display Unit) because it provides all the result to the user visually It is also known as soft copy output device, Because we can't touch the data displayed on it and we can easily edit the data on it the monitors are different types according to its technology such as;
- Monochrome Monitor: - Provide the result in black and white display.
- Color Monitor: - Provides the result colorful.
- CRT Monitor (Cathode Ray Tube):- This type of monitor uses one vacume tube which is known as cathod Ray tube to display the image and objects.
- LCD (Liquid Crystal Display):- It is more advanced than CRT monitor. It is very thin in size and uses the liquid crystal to form objects.

Printer: - It is known as hand copy output device, when we give print command to the computer, the printer gives the result at printed form on the paper. So we can easily touch the printed data. But we can not edit the printed data. We can categorize the printer into two types. They are;-
i) Impact Printer: - The printer which hits on the paper while printing is known as impact printer. Such as Dot Matrix Printer.
ii) Non Impact Printer: - The printer which sprays the liquid or powder ink at the paper to form on object is known as non- Impact printer it doesn't hit at the paper while printing. Such as Bubble jet printer , laser printer
Plotter: - It is also hand copy output device. Especially this device is used to print the high Quality graphics in large size.Motherboard: - It is the main PCB (Printed Circuit Board) of Computer. The main work of this board is to flow the data from one location to another it contains different sections and it have its own speed which is known as but speed. (Data transfer speed)
It have the microprocessor socket to connect the microprocessors, RAM slots, PCI slots, ISA slots, AGP slots, H.D.D. controller, F.P.P. Controller, keyboard Controller and other sections.
Processor: - It is used to process the raw data input by using different types of input device. It has its own processing speed. It is connected at processor socket of motherboard
RAM (Random Access Memory) It is temporary memory of computer. It can store the data while the electricity is flowing
H.D.D. (Hard disk drive):- It is permanent storage Media of Computer. It stores all the operating system, programs and all the files and folder of the computer, It have it's own storage capacity
CDROM: - It can read the data of CD's – especially this device is used to read and display the contains of the CDS.
F.D.D. (Floppy disk drive):- the drive which is used to operate 1.44 MB floppy disk. The main work of this device is to read and write the data on the floppy disk.

Input Device of Computer

1. Keyboard: It is known as primary input device. It is also known as typing device, because we can input the data and instruction by typing. It have different types of key combination such as, alphabetical keys (A to Z), numerical keys (0 to9), Function keys (F1 to F12) Arrow keys (Right, Left, Down and up) and other keys, Most of the keyboard have QWERTY layout; The keyboard have 102 to 108 keys and in FCC standard
2. Mouse: - It is other types of input device and also known as pointing device. By using the mouse pointer we can perform the works at computer. When we move the mouse the pointer will move to the same direction and when we click in certain command field the work mentioned at the command field will be performed. The mouse has to buttons (left and right). The left button is used for normal work and right button is used for other works. The stroller of mouse is used to move the working file up a down. The mouse is of three types they are Serial Mouse, Ps/2 Mouse and USB Mouse.
3. Scanner: - It is also another type of input device of computer. Especially this device is used to convert the hand copy data into soft copy and send the data to the computer. Basically used to input the picture files to the computer.
4. Digital Camera: - We can use this device to input the digital picture files to the computer we can connect the digital camera at computer by suing the USB port.
5. Joystick: - It is one type of control device, which is used for gaming option. This device is specially designed to play game at computer.
6. Light pen: - It has the light sensitive detector at its tip and it generates the light we should use this device at the pad, when we write something at pad the hand writing will input to the computer also it as known as input device.

COMPUTER parts


Computer is an electronic device which accepts the raw data as input processes them and gives the desired result to user.
According to this definition we can find three types of devices in a set of computer they are 11. Input device :- The device which is use to feed raw data to the computer is known as input device such as, Keyboard, Mouse, Digital Camera, Scanner, light pen, Joystick
2. CPU: - It is the main Machine of the computer. It is also known as brain of computer, All the words will be performed in this unit and stores also.
3. Output Device :- The device which is used to get the result of work done at computer is known as output device such as; Monitor, Printer, Plotter

Wednesday, July 21, 2010

. Out Put device

Monitor: It is primary output device of computer and also known as VDU (Visual Display Unit) because it provides all the result to the user visually It is also known as soft copy output device, Because we can't touch the data displayed on it and we can easily edit the data on it the monitors are different types according to its technology such as;
- Monochrome Monitor: - Provide the result in black and white display.
- Color Monitor: - Provides the result colorful.
- CRT Monitor (Cathode Ray Tube):- This type of monitor uses one vacume tube which is known as cathod Ray tube to display the image and objects.
- LCD (Liquid Crystal Display):- It is more advanced than CRT monitor. It is very thin in size and uses the liquid crystal to form objects.
Printer: - It is known as hand copy output device, when we give print command to the computer, the printer gives the result at printed form on the paper. So we can easily touch the printed data. But we can not edit the printed data. We can categorize the printer into two types. They are;-
i) Impact Printer: - The printer which hits on the paper while printing is known as impact printer. Such as Dot Matrix Printer.
ii) Non Impact Printer: - The printer which sprays the liquid or powder ink at the paper to form on object is known as non- Impact printer it doesn't hit at the paper while printing. Such as Bubble jet printer , laser printer
Plotter: - It is also hand copy output device. Especially this device is used to print the high Quality graphics in large size.
CPU :-
Motherboard: - It is the main PCB (Printed Circuit Board) of Computer. The main work of this board is to flow the data from one location to another it contains different sections and it have its own speed which is known as but speed. (Data transfer speed)
It have the microprocessor socket to connect the microprocessors, RAM slots, PCI slots, ISA slots, AGP slots, H.D.D. controller, F.P.P. Controller, keyboard Controller and other sections.
Processor: - It is used to process the raw data input by using different types of input device. It has its own processing speed. It is connected at processor socket of motherboard
RAM (Random Access Memory) It is temporary memory of computer. It can store the data while the electricity is flowing
H.D.D. (Hard disk drive):- It is permanent storage Media of Computer. It stores all the operating system, programs and all the files and folder of the computer, It have it's own storage capacity
CDROM: - It can read the data of CD's – especially this device is used to read and display the contains of the CDS.
F.D.D. (Floppy disk drive):- the drive which is used to operate 1.44 MB floppy disk. The main work of this device is to read and write the data on the floppy disk.
History of Computer
The Computer was developed from the development of Abacus which was developed 3000 thousand year ago in China. It is one type of counting device which has two sections Heaven and Earth. By moving (Manipulating) the beds of heaven and Earth the counting works will be performed.
After the development of this device in different time period different types of advanced devices were developed. Such as; Napier's bone
Slide rule
Pascaline
The Computer is also developed by using these steps.
In 1946
According to this development of devices into different time period the computer can be categorized into different generation. They are ;
1. First Generation (1946-1958) :- In this time period the computer was developed for the first time. In this time period the memory devices was used in Computers. Which is known as vacume tube?
Features of Generation Computer
- It was very big in Size.
- It uses vacume tube as main memory.
- In this generation of Computer required more electricity (Power) up to 30 KB.
- It was very slow in processing.
- It generates more heat.
2. Second Generation (1958-1964) :- The development of Computer between the time period 1959 to 1964 is known as second Generation. In this generation the technology was developed than first generation.
Features of generation Computer
- It was transistor as main memory
- The size of computer was reduced than first generation
- It has high processing speed than previous generation
- It required less electricity than first generation.
3. Third Generation (1965-1974)
The development of Computer in this times period it known as third generation computer. In this time period the computer was more advanced and reliable.
Features of third generation
- IC was use as main memory and circuit.
- The size was also reduced then previous generation
- The processing speed was increased and memory capacity was also increased.
- It uses less electricity power than previous generation.
- All types of normal software can be easily run in this computer. So it provides friendly environment to the user.
Fourth generation computer (1975- Till)
The computer which we can use now days is known as fourth generation of computer. It has high processing speed and more storage capacity. It also can be categorized in different such categorized such as; Pentium one; Pentium 2 , 3 and 4.
Features of Forth generation
- VLSI and VVLSI were used as main chip.
-Processing speed was developed up to GHZ
- It has more storage capacity than pervious generation
- The storage capacity it up to GB.
- The size of this generation computer is decreased up to laptop computer.
- Ti required low electric power up to twelve volt.
Fifth generation of computer (not started)
The fifth generation of computer has been expected self thinking capacity and understood the human language. The Biochips are used as main components of computer.

Input Device of Computer

Keyboard: It is known as primary input device. It is also known as typing device, because we can input the data and instruction by typing. It have different types of key combination such as, alphabetical keys (A to Z), numerical keys (0 to9), Function keys (F1 to F12) Arrow keys (Right, Left, Down and up) and other keys, Most of the keyboard have QWERTY layout; The keyboard have 102 to 108 keys and in FCC standard
Mouse: - It is other types of input device and also known as pointing device. By using the mouse pointer we can perform the works at computer. When we move the mouse the pointer will move to the same direction and when we click in certain command field the work mentioned at the command field will be performed. The mouse has to buttons (left and right). The left button is used for normal work and right button is used for other works. The scroller of mouse is used to move the working file up a down. The mouse is of three types they are Serial Mouse, Ps/2 Mouse and USB Mouse.
Scanner: - It is also another type of input device of computer. Especially this device is used to convert the hand copy data into soft copy and send the data to the computer. Basically used to input the picture files to the computer.
Digital Camera: - We can use this device to input the digital picture files to the computer we can connect the digital camera at computer by suing the USB port.
Joystick: - It is one type of control device, which is used for gaming option. This device is specially designed to play game at computer.
Light pen: - It has the light sensitive detector at its tip and it generates the light we should use this device at the pad, when we write something at pad the hand writing will input to the computer also it as known as input device.

COMPUTER

Computer is an electronic device which accepts the raw data as input processes them and gives the desired result to user.
According to this definition we can find three types of devices in a set of computer they are
Input device :- The device which is use to feed raw data to the computer is known as input device such as, Keyboard, Mouse, Digital Camera, Scanner, light pen, Joystick
CPU: - It is the main Machine of the computer. It is also known as brain of computer, All the words will be performed in this unit and stores also.
Output Device :- The device which is used to get the result of work done at computer is known as output device such as; Monitor, Printer, Plotter