HARDWARE - Storage

Storage

Primary Storage (RAM, ROM) - Primary storage is the main memory in a computer. It stores data and programs that can be accessed directly by the processor. There are two types of primary storage which are RAM (Random-Access Memory) and ROM (Read-Only Memory). RAM is installed inside computers. RAM is also known as a working memory.

• Random-Access-Memory (RAM )- The data in RAM can be read (retrieved) or written (stored). RAM is volatile which means the programs and data in RAM are lost when the computer is powered off. Computer uses RAM to hold temporary instructions and data needed to complete tasks. This enables CPU to access instructions and data stored in the memory very quickly. RAM stores data during and after processing.
• Read-Only-Memory (ROM) - ROM is another type of memory permanently stored inside the computer. ROM is non-volatile. It holds the programs and data when the computer is powered off. Programs in ROM have been pre-recorded. It can only be stored by the manufacturer; once it is done, it cannot be changed. Many complex functions, such as start up operating instructions, translators for high-level languages & operating systems are placed in ROM memory. All the contents in ROM can be accessed and read but cannot be changed.

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Secondary Storage (magnetic medium optical medium, flash memory)

Secondary Storage is another alternative storage device to keep your work and documents. It is very useful to store programs and data for future use. It is installed externally. It is non-volatile, which means that it does not need power to maintain the information stored in it. It will store the information until it is erased.

Secondary storage can be divided into magnetic medium, optical medium and flash memory.

• Magnetic Medium - Magnetic medium is a non-volatile storage medium. It can be any type of storage medium that utilizes magnetic patterns to represent information. The devices use disks that are coated with magnetically sensitive material. The examples of magnetic storage are magnetic disk ( floppy disk, used for off-line storage, hard disk, used for secondary storage), magnetic tape ( video cassette, audio storage reel-to-reel tape & others)

• Optical Medium - Optical medium is a non-volatile storage media that holds content in digital form that are written and read by a laser. These media is usually a flat, circular portable disc which include various types of CDs and DVDs. These following forms are often commonly used:
• CD, CD-ROM, and DVD are a read-only storage, used for distribution of digital information such as music, video and computer programs.
• CD-R is a type of optical storage where it can be written once and cannot be erased or written over once it is saved.
• CD-RW, DVD-RW, and DVD-RAM allow data that have been saved to be erased and rewritten It is however slow to write but fast reading type of storage.

The disk capacity of optical media is more compared to magnetic media. Durability is another feature of optical media; they are able to last for up to seven times as long as traditional storage media.

• Flash Memory - Flash Memory is a solid-state, non-volatile, rewritable memory that functions like RAM and a hard disk drive combined. Flash memory store bits of electronic data in memory cells just like DRAM (Dynamic RAM), but it also works like a hard disk drive that when the power is turned off, the data remains in the memory. Flash memory cards and flash memory sticks are examples of flash memory.

Flash memory cards are also used with digital cellular phones, MP3 players, digital video cameras and other portable digital devices. Flash memory is also called USB drives, thumb drives, pen drives or flash drives, are the up-and-coming players in the portable storage market.

The advantages of flash memory are, it offers faster reading or access time compared to other secondary storage devices, (though not as fast as RAM) it is durable and requires low voltage. It is also light and small. The disadvantage is it is more expensive than the magnetic disk of the same capacity.