Computer Memory and storage

It is an internal storage area in the Computer System. The term Memory is used for physical memory, which refers to the actual chips capable of holding data. There is also a virtual memory, which expands physical memory onto a hard disk. There are two types of mnemory use in Computer Primary and secondary.

The term memory can be categorized in two parts- ...

1- Primary Memory

2- Secondary Memory

(i) Primary Memory

Every Computer comes with a certain amount of physical memory, usually referred to as main memory or primary memory. 

For Example RAM and ROM

RAM- (Random Access  Memory)

It is a temporary (Volatile) storage area utilized by the CPU, Before a program runs, the programs loaded into the memory which allows the CPU direct access to the program.

SRAM : Abbreviation is Static Random Access Memory that is faster and more reliable than the more common DRAM (Dynamic RAM). The term Static is derived from the fact that it doesnt need to be refreshed like Dynamic RAM. SRAM İs often used only as a memory cache usually found in the CPU (L1, L2 and L3 Cache).

DRAM : Stands for Dynamic Random Access Memory, a type of memory used in most Personal Computers 

SDRAM: Stands for Synchronous DRAM, a new type of DRAM that can run at much higher clock speeds than conventional memory. SDRAM actually synchronizes itself with the CPU.

DDR2-SDRAM:Abbreviation is Double Data Rate Synchronous DRAM 2 is a type of DDR that supports higher speed than its ancestor DDR SDRAM.-

DDR3-SDRAM : Abbreviation is Double Data Rate Synchronous DRAM 3 is the newest type of DDR that supports the fastest speed of all the SDRAM memory.

ROM ( Read Only Memory)

Computer always contain a small amount of read-only Memory that holds instructions for starting up the computer. Unlike RAM, ROM Cannot be written to. It is non volatile which means once you turn off the computer the information is still there

PROM ( Programmable Read - Only Memory)

A PROM is a memory chip on which data can be written only once. The difference between a PROM and a ROM is that PROM is Manufactured as blank memory.whereas a ROM is programmed during the manufacturing process.

EPROM (Erasable Programmable Read-Only Memory)

I is a special type of PROM that can be erased by exposing it to ultraviolet light. Once it is Erased, it can be reprogrammed. An EEPROM is similar to a PROM, but requires only electricity to be erased.

EEPROM (Electrically Erasable Programmable Read-Only Memory)

Pronounced double-EE-PROM or e-e-prom, an EEPROM is a special type of PROM that can be erased by exposing it to an electrical charge. Like other types of PROM, EEPROM retains its contents even when the power is turned off. Also like other types of ROM, EEPROM is not as fast as RAM. EEPROM is similar to flash memory (sometimes called flash EEPROM).

(ii) Secondary Memory 

These types of memories are internal or external storage devices either inside or outside the Computer. It store programs and data permanently, you can access anytime when attached to the computer. You cannot store the data in primary memory permanently and primary memory costs higher than secondary memory. It is slower, but cheaper. Floppy disks, hard drives, CD, DVD Pen drive etc are secondary storage devices. The secondary storage can be divided into Magnetic device, Optical Device and Flash Memory.

Floppy Disk

It is removable device or data traveler and re- writable. floppy disk is flat, circular pieces of Mylar Plastic that rotate within a jacket. The size of floppy is 3.5 inches and storage capacity of floppy Disk is 1.44 MBe

Hard Disks (Hard Drives)

A Hard disk is a Magnetic disk made of metal and covered with a magnetic recording surface Now-a-days there are huge capacitive Hard disks available in the market to store the data lilk ,500GB, 1TB, 30TB and even greater.

Optical Disk

Optical disk is a disk read and written by laser beam. Optical disk does not need to move access arms and read/write heads, because a laserbeam can be moved electronically. For writing data, a laser beam burns tiny cavities into the surface of a disk to mark bits for data. To read the data a laser beam scans these areas.

There are kinds of Optical disks available...

Write Once Read Many Disks (Normal CD) 

This kind of optical disks are plain and simple and easy to write the data once only and that after you can not re-write that disk ever but you can access or read it many times you want. This kind of optical disks contain upto 700 MB data.

Re-writable Optical Disks

This is an optical disk that can be erased and written upon repeatedly. An erasable optical disk has a great deal of data capacity. This kind of optical disks cost little higher than normal CDROMs.

CD-ROM (Compact Disk Read Only Memory) 

This kind of Secondary memory device is an optical disk that is written upon once only by the user's environment and then cannot be re-written.

DVD (Digital Video Disk)

It is even known as Digital Verstile disk.lt is mass storage disk comes normally upto 4.7 GB and in special case it comes even upto 45 to 50 GB.This uses digital technology to store data in concized form.It stores more than a normal Compact disk.

Mass Storage Devices 

Mass Storage device is referred as the storage device which can hold moredatathan normal storage device.

USB Thumb drive 

USB thumb drive normally known as flash drive or pen drive is used to store bulk data as per its capacity. they are small in size with a USB face is portable to be used any where any computer. This is little faster comparetively.