Optical memory by sonal

This is about one of the memory types that is optical memory.It will help you to know about optical memory.

1. BY- Sonal Srivastava B.Tech (CSE) 4 th Sem. Presentation on- " OPTICAL MEMORY "

2. Memory is a storing device. It is used to store data and information. It is an essential component of a digital computer. WHAT IS A MEMORY???

3. There are three types of memory- SEMICONDUCTOR MEMORY Ram Rom MAGNETIC MEMORY OPTICAL MEMORY TYPES OF MEMORY-

4. Laser beam is used to write or read information. It has a very high storage density and data integrity. It is relatively inexpensive and has a long life. Optical disk is removable from the computer. OPTICAL MEMORY-

5. CD-ROM(Compact disk read only memory) WORM(write once read many) MAGNETO-OPTICAL DISKS DVD-ROM,DVD-R & DVD-RAM FLOPTICAL DISKS TYPES OF OPTICAL MEMORY-

6. It is Compact Disk Read only memory. Information is written to the disk by burning pits on the disk surface with controlled laser beam. The disk is made of resin,such as polycarbonate. It is coated with a highly reflective surface ,usually aluminium . CD-ROMs do not use concentric tracks . They use single spiral tracks . CD-ROM-

7. The disk size is 5.25 inch diameter. track density is 16000 tracks per inch. The capacity of CD-ROM is 600 MB,2048 bytes of information are stored per sector. Access time is about 80 ms of new disks. Access time for earlier disks is 250 ms. Data transfer rate is about 4800KB/sec. SIZE & SPEED-

8. The user can write data only once. A laser beam is used to write information on the disk. The written data can be read as many times as desired. They store permanent information for record. One can rewrite modified or some new information to another portion of the disk. One can not modify data which has already been written. WORM- (WRITE ONCE READ MANY)

9. The size of disk is 5.25 inch diameter. The capacity of WROM is 650 MB. It has high capacity better reliability and longer life. It runs at constant speed to reduce access time. Its tracks are concentric circles . Each track is divided into a number of sectors. It has longer access time compared to hard disks. SIZE & SPEED-

10. Also known as erasable optical disk. It is a read write laser assisted magnetic memory. Info can be written to or read from the disk as many times as required. The read/write head contains a laser beam and a current coil. A magnetic field perpendicular to the disk surface can be produced by passing current through coil. It writes info when magnetic material is heated by laser beam. MAGNETO-OPTICAL DISK-

11. Available in 5.25 inch or 3.5 inch diameter. Storing capacity of 5.25 inch disk is 650 MB,5.2GB etc. Capacity of 3.5 inch disk is 1.3 GB. It has high density,long life,portability & better reliability. It is slower in access. Data transfer is slower as compared to hard disk. SIZE & SPEED-

12. These are high capacity floppies. They use laser beam to mark tracks and sectors. They have more tracks & sectors than ordinary floppies. Read/write operation is done as in ordinary floppies. These are removable. It uses surface coating of barium ferrite. FLOPTICAL DISKS-

13. It is a kind of magneto-optical disk. Its speed is same as magneto-optical disk. It uses a 3.5 inch disk shell. Its capacity is about 120 MB. A floptical drive can also read/write standard 3.5 inch floppies.. SIZE & SPEED-

14. These are digital versatile disks ROMs. They store much more data as compared to CD-ROMs. It is double sided & have dual layers. It contains a thick polycarbonate plastic which provides a base for other layers. The next layer is a thin opaque layer of reflective material. Then a thin layer of transparent film & a protective layer is used. DVD-ROMs-

15. It is a read/write optical memory. It uses phase change technology to read,write and erase data. The laser beam is focussed on a reflective layer made of silver ,indium & tellurium embedded in a plastic base. In the normal state the reflective layer has crystalline structure. To erase the data low energy laser beam is used. DVD-RAM-

16. DVD-R is once writable optical disk. It is a recordable DVD. It is similar to WORM. Its size,capacity & speed is same as WROM. DVDs use shorter wavelength of light than CD does. The capacity of DVD-ROMs is 4.7 to 17 GB.

17. THANK YOU …!!!