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Input And Output Devices

15 Input Devices 10 Output Devices Devices Work As Both Input And Output  Modem Network card Touch Screen Headsets Facsimile (FAX) Modem  - As we know that analog signals transfer in phone line but computer understands only digital signals, so to convert the analog signals into the digital signal and vice-versa modem is used. Modem is considered as both input and output device. Network  Card -  A  Network  card (also known as a  NIC or   network interface card ) is an electronic device that connects a computer to a computer  network. With the help of NIC data we receive and send data so NIC works as both input and output device. Touch Screen  –  A touchscreen is a both input and output device and normally layered on the top of an electronic visual displays such as cell phone, laptop. A user can give input or control the information through simple or multi-touch gestures by touching the screen. Headset  - Headset consists of Speakers and Micr
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Computer Memory


Computer Memory


Memory - The data and instructions that are entered into the computer system must be stored inside the computer before the actual processing can start. Similarly, the results produced after processing must also be stored before they can be passed on to the output unit. Computer has two basic types of Memory Primary Memory (RAM, ROM) Secondary Memory (Hard drive, Memory card).

Functions of the primary memory

  1. All data and instructions to be proceed.
  2. Intermediate results of processing
  3. Final results before sending them to output devices

Types of Computer Memory 


Types of Computer Memory
Types of Computer Memory

Computer Memory

  1. Primary Memory
  2. Secondary Memory

PRIMARY MEMORY - Primary memory is volatile (not permanent) memory. All instructions at first reach in Primary Memory. All the information will be lost if power is gone.

Types of primary memory

  1. RAM
  2. ROM

RAM - Random Access Memory is a read/write memory. Information can be written into and read from a RAM. It is a volatile memory which means, that it retains the stored information as long as the computer is connected to a power supply source. When power supply is switched off or interrupted the stored information in the RAM is last. RAM is available in various capacities, for example, 4 GB, 8 GB and so on.

Random Access Memory



Types of RAM


  1. SRAM             
  2. DRAM


SRAM – SRAM stands for Static Random Access memory. SRAM storage is based on the logic circuit known as Flip-flop, which retains the information stored in it as long as there is enough power to run the device. They do not need refreshing circuitry and have higher speed than dynamic RAM.

DRAM - Dynamic random access memory (DRAM) loses its stored information in a very short time (a few milliseconds) even when the power supply is on. Therefore, dynamic RAMs have to be refreshed periodically; generally every 2 milliseconds Dynamic RAM are cheaper and have high packing density with moderate speed. They also consume less power and are used when a large capacity of memory is needed.
                                 

ROM - ROM stands for Read Only Memory. ROM is a permanent type of memory.  ROM is a class of storage media used in computers and other electronic devices. ROM is mainly used to distribute firmware (software that is very closely tied to specific hardware and unlikely to require frequent updates). All the starting instructions (Booting instructions) are stored in ROM. These instructions are built into the ROM by the company during manufacturing time. 

Read Only Memory

Types of ROM

  1. PROM (programmable read-only memory)
  2. EPROM (erasable programmable read-only memory)
  3. EEPROM (electrically erasable programmable read-only memory)


For detail information about ROM kindly visit Wikipedia



Secondary Storage – You cannot store data in the main memory of a pc permanently. Firstly because it is very expensive and secondly its contents are erased when computer is turned off. In order to store information permanently you need storage media such as Hard Disk, CD, DVD, Pen Drive etc.

Types of Secondary Storage

  1. Hard Disk Drive
  2. CD
  3. DVD
  4. Pen Drive
  5. Memory Card

Storage Techniques


Magnetic Tape is a sequential storage device but now it is outdated from market. Hard Disk is Random Access Device. CD/DVD has Optical storage technique.

Hard Disk - A hard disk drive (HDD) is an electro-mechanical data storage device that uses magnetic storage to store and retrieve digital data using one or more rigid rapidly rotating platters that are coated with magnetic material that allows data to be magnetically recorded on the surface of the platters. The hard disk platters spin at high rate of speed, typically 5400 to 7200 revolutions per minute (RPM). The storage capacity of the hard disk for the personal computer ranges from 500 GB to 4 TB. 

hard disk drive (HDD)


CD (Compact Disk) - Their storage capacity is 700 MB. Since it is very reliable storage media, it is very often used as a medium for distributing large amount of information to large number of users. In fact today most of the software is distributed through CDs.

CD (Compact Disk)


DVD Digital Versatile Disk (DVD) - It is similar to a CD but has larger storage. A normal DVD can store 4.7 GB of data while a SDVD (Super DVD, also called dual layer DVD) can store up to 7GB of data. These are not rewritable media. It is also known as Digital Video Disk.

DVD Digital Versatile Disk (DVD)

Pen Drive – Pen drive also known as USB flash drive is a small removable rewritable drive. Pen drive is available in various sizes from 8GB to 512GB.

Pen drive



Memory Card  -  A memory card is an electronic data storage device used for storing digital information. These are commonly used in portable electronic devices, such as digital cameras, mobile phones, computers, tablets, video game consoles.

Memory Card



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