The Memory Devices
- Memory is an essential area which is needed to store the data.
- Without memory storage, it is not possible for the computer to perform any task.
- It helps in storing and retrieving data.
- There are two types of memory available
- They are
- Primary memory or Main Memory
- Secondary memory
- It is used as a component, device and recording media that stores digital data used for computing, for some interval of time.
- It is one of the preliminary components of all modern computers and merged with a CPU.
- Semiconductor is used to store the data as a memory location.
- There are two types of primary memories
- They are
- Random Access Memory (RAM): It is a semiconductor storage and fast but it is a temporary storage.
- Read Only Memory (ROM): It is a memory unit that performs read only operation. It is a non-volatile memory. Once the program is written, if the system is shut down the data will remain in the memory. They are of many types. They are
- PROM - Programmable Read Only Memory
- EPROM - Erasable Programmable Read Only Memory
- EEPROM - Electronically Erasable Programmable Read Only Memory
- OROM - Optical Read Only Memory
|Note: OROM is used to store Holographic data.|
Secondary Memory Devices (Secondary Memory)
- All computer data cannot be stored in the primary memory, where it does not have enough memory to store.
- Hence we use the secondary storage devices to store data.
- They are transferable, portable and easy to use
- They are as follows
- Hard disks
- Floppy disks
- Compact Disk Read only memory
- Digital versatile disk
- It is a permanent storage device.
- It is not possible for the PC to work without this hard disk
- It stores data in a circular platters or disks.
- The information is stored in the surface of the rotating disk by magnetic heads as a tiny magnetic spots.
- The following figure explains the part of the hard disk.
- Its capacity of storage starts from 10 MB, 40 MB and so on.
- The latest storage capacity of a hard disk is .1 GB(Giga Byte)
|Note: The circular path has a set of concentric circles in the hard disk called the tracks. The track contains the data.|
It is a portable and removable device.
It is capable to storage data of 1.44 Mb.
It stores fewer amounts of graphical data like sound, video, images and animation.
They are made of flexible plastic disks coated with magnetic material on both the sides.
For safety, they are placed inside a protective plastic envelope, which is provided with a slot for reading and writing data on the surface of the disk.
Data is written on the disks in the form of tiny magnetic spots.
The floppies have labels to identify their data contents and an index hole to indicate the starting location on the floppy.
The following figure shows the part of the floppy disk and its appearance.
There were various size of floppy disk in the olden days.
They are shown below.
Compact Disk (CD-ROM)
- These players are an integral part of the multimedia development of workstation, and are an important delivery vehicle for large, mass-produced projects.
- They are optical devices which are written in laser.
- The data stored are Read Only.
- Their capacity is up to 700MB
- They are of different types
- CD-R: Compact Disk Recordable
- CD-RW: Compact Disk Rewritable.
|Note: These devices are used to store all types of data like images, video, sounds, movie etc.|
Digital Versatile Disk
- It is an optical storage device.
- It is also called Digital Video Disk.
- It is mainly used for video and storage.
- It is a multilayered disk; hence it stores more amount of information.
- They are called as Super density disk (SD)
- There are of many varieties. They are
- DVD-R (DVD- Recordable)
- DVD-RW (DVD-Rewritable)
|Note: Blu-ray is a next generation optical device to transfer data.|