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 virtual memory, which expands physical memory onto a hard disk. There are two types of memory used in computers primary and Secondary.

Memory Units

4 Bit

1 Nibble

8 Bit

1 Byte

1024 Bytes

1 Kilobyte (KB)

1024 Bytes

1 KB

1024 KB

1 Mega Byte (MB)

1024 MB

1 Giga Byte (GB)

1024 GB

1 Tera Byte (TB)

1024 TB

1 Peta Byte (PB)

The term memory can be categorized into two parts-

Primary Memory- Every computer comes with a certain amount of physical memory, usually referred to as main memory or primary. 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 program is located in 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 does not need to be refreshed like a dynamic ram. SRAM is often used only as a memory cache usually found in the CPU.

DRAM: stand for dynamic random-access memory, a type of memory used in most personal computer.

SDRAM: stands for synchronous dram, a new type of dram that can run at much higher clock speeds than conventional memory. SDRAM synchronizes itself with the CPU.

DDR2-SDRAM: abbreviation is double data rate synchronous dram 2 is a type of DDR that support 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)

The computer always contains 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 (read-only memory) is that a prom is manufactured as blank memory whereas a ROM is programmed during the manufacturing process.

EPROM (erasable programmable read-only memory)

It 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 (Electricity 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 electric charge. Like another type of prom, EEPROM retains its contents even when the power is turned off. Also, like another type of ROM, EEPROM is not as fast as a ram. EEPROM is similar to flash memory (sometimes called flash EEPROM.

Secondary memory

These types of memory are internal or external storage devices either inside or outside the computer. It stores programs and data permanently; you access it anytime when attached to the computer. You cannot store the data in primary memory permanently and primary costs are higher than secondary memory. It is slower but cheaper. floppy disks, hard drives, CD DVD pen drives, etc. are secondary storage that can be divided into magnet devices ice, optic device, and flash floppy

Floppy disk

It is a removable device or data traveler and is re-writable. A floppy disk is flat, circular pieces of mylar plastic that rotate within a jacket. The size of the floppy is 3.5 inches and the storage capacity of the floppy disk is 1.44 MB.

Hard disks

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 like 500 GB,1 TB,30 TB, and even greater.

The Hard Disk drive has the following components.

Platter

The fixed disk within the hard disk drive, there can be several platters within the hard drive.

Heads

Each side of a platter.

Tracks

The large section completely circles the platter.

Sector

The section on the track.

Cluster

Smallest units of measurement that a hard drive will read.

Cylinder

Tracks of the same diameter or each platter.

Optical Disk CD ROM

This kind of storage device comes under a secondary storage device whereas CD-ROM is a driver to access or read an optical disk. Here we will discuss in detail…….

Optical Disk

The optical disk is a disk read and written by a laser beam. The optical disk does not need to move access arms and/or write heads, because a laser beam 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.

 

Optical Disk