Its a output device similar to a printer that uses a pen, pencil, marker or other writingtoolto make a design. Plotters are generally used to generate the map of otter building and shopping malls. A plotter is a computer printing device for printing vector graphics. In the past, plotters were widely used in applications such as Computer Aided Design (CAD) and other print jobs. Though they have generally been replaced with wide-format conventional printers
There are two basic types of plotters those that use pens and those that do not. Drum plotters and flatbed plotters use pens but electrostatic plotters do not use the same.
(i) Drum plotter A drum plotter contains a long cylinder and a pen carriage. The output paper is placed over the drum. The pen is mounted horizontally on the carriage. Both the pen and drum move under the computer’s control to produce the desired drawing.
(ii) Flatbed plotter A flatbed plotter consists of a stationary horizontal flat surface on which paper or any other medium is fixed. The pen is mounted on a carriage that can move along the horizontal and vertical axis.
(iii) Electrostatic plotter it mark paper with electrostatic charges and run it through a developing system to create an image. They produce high-quality images and are used by graphic and commercial artists.
Speaker is an output device that receive the sound in the form of electric current from the sound card and convert it into sound format. Speakers are used for listening to music.
Computer speakers (multimedia speakers) are the speakers which are attached internally or externally to a computer system.
Headphones are a pair of small loudspeakers or less commonly a single speaker, held close to a user’s ears and connected to a signal source such as an audio amplifier, radio, CD player or portable media player.
They are also known as stereo phones, headsets or cans.
it is an output device, which is used to project information from a computer onto a large screen, so it can be viewed by a large group of people simultaneously.
Projectors are widely used for classroom training or conference holes with a large audience. It provides a temporarY output display.
Speech synthesizer is used to produce sound from a text and can be implemented in software and hardware. A text to speech system convert normal language text into speech.
The computer memory is one of the most important elements in a computer system. It is the internal or external storage area, which holds the data and instructions during processing in the form of binary numbers.
It also relates to many devices and components that are responsible for storing data and applications on a temporary or a permanent basis.
Computer memory can be classified into two
(i) Primary memory and
(ii) Secondary memory/Storage device.
It is also known as Main Memory. It is the internal storage memory used by computer to hold data and instructions. The primary memory has limited storage capacity.
Primary memory holds the data and programs needed at that instant by CPU.
Primary memory is volatile in nature i.e. it requires constant power supply to motion the current information.
There are two types of Primary Memory:
RAM stands for Random Access Memory. It is the internal memory that can be read from as well as written to. ‘‘h RAM memory is often associated with volatile types of memory. It can hold data only on temporary basis because it requires a continuous flow of electrical current.
If current is interrupted, data is lost, it is an integrated circuit that enables you to access the stored data in a random order constantly.
lie two main forms of RAM are:
(a) Static RAM It is also written as S RAM. It is a computer memory that requires a constant power flow in order to hold information. S RAM is more expensive and requires more power therefore it is commonly used in cache and video card memory. It is faster than DRAM.
(b) Dynamic RAM It is also written as DRAM. It stores information in a cell containing a capacitor and transistor, these cells must be refreshed with electric impulses in few milliseconds. This process allows memory to keep charge and hold the data as long as needed.
There are some enhanced versions of RAM, hich are as follows:
- a) EDORAM (Extended Data Output Random Access Memory)
(b) SDRAM (Synchronous Dynamic Random Access Memory)
c DDR SDRAM (Double Data Rate Synchronous Dynamic Random Access Memory)
In ROM (Read Only memory). memory, once stored main fixed, i.e. it can not changed. So, ROM can ROM
dv be read and used. Generally, it contains a set of start-up liructions, i.e. what to do when a computer is ued ON. The contents of ROM remain stored lcn if power is turned OFF. This memory is often coated with non-volatile types of memory. A DM cannot be altered once the chip has been .de.
DM is further sub divided into several types:
(a) PROM (Programmable Read Only Memory) It is a computer memory chip capable of being programmed after it has been created. But once the PROM has been programmed, the information written is permanent and cannot be erased or deleted.
(b) EPROM (Erasable Programmable Read Only Memory) It is a computer memory chip on which the written information can be changed by exposing to ultra voilet light. It is just like a small glass circle that expose the chip that can be re-programmed.
(c) EEPROM (Electrically Erasable Programmable Read Only Memory) It is a PROM that can be erased and reprogrammed using an electrical charge.
Cache (pronounced cash) memory is extremely fast memory that is built into a computer’s central processing unit, or located nect to it on a separate chip. The Cpu uses cache memory to store instructions that are repeatedly required to run programs, improving overall system speed. As the microprocessor processes data, it first looks in the cache memory and if it finds the data there (from a previous reading of data), it does not have to do the time-consuming reading of data from larger memory. The advantage of cache memory is that if needed data is found in cache then the cu does not have to use the motherboard’s system bus for data transfer and thus processing gets fast.
Storage Devices/Secondary Memory
Secondary memory, also known as Secondary Storage or Auxiliary Memory, is the slower and cheaper form of memory. It is a permanent storage device.
CPU does not access the secondary memory directly. The content in it must first be copied into the RAM to be processed. Secondary memory is non-volatile in nature. i.e. the information does not get erased even when power is switched OFF and data will not be destructed until and unless the user erases it.
Secondary Memory devices include
Magnetic disks Optical discs Solid State
Fbppy Disk CD Pen/Hash Drive
Hard Disk Drive DVD ______
Magnetic Tape Blue-ray Disc
(i) Floppy Disk (Diskette)
A Floppy Disk Drive (FDD) is a computer disk drive that enables a user to save data on removable diskettes. This portable storage device is a rewritable media and can be reused a number of times. It is made of plastic with magnetic coating on it. It is round in shape and is covered by square plastic jacket.
Floppy disks are commonly used to move ifies between different computers. Although 8” disk drives made available in 1971 were the first real disk drives, the first widely used floppy disk drives were the 4”, 5 floppy disk drives, which were later
replaced with 3 floppy disk drives.
However, today these drives are being replaced with CD-R and other writeable disc drives and flash drives. MB. diameter-floppy has a capacity of 1.2 3 diamel. -floppy has a capacity of 1.44 MB.
(ii) Hard Disk Drive
A Hard Disk Drive (HDD) is a non-volatile, random access digital data storage device. It is a data storage device used for storing and retrieving digital information using rotating disks (platters) coated with magnetic material. All programs of a computer are installed in hard disk within a particular drive.
It consists of a spindle that hold non—magnetic flat circular disks, called platters, which hold the recorded data. Each platter requires two read/write heads, that is used to write and read the information from a platter. All the read/write heads are attached to a single access arm so that they cannot move independently.
The information is recorded in bands, each band of information is called a track. Each platter has the same number of tracks and a track location that cuts across all platters is called a cylinder. The tracks are divided into pie-shaped sections known as sectors.