Memory Units and Secondary Memory for UCO

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Memory units

• Storage capacity is expressed in terms of Bytes.

• The Data is represented as binary digits (0s and 1s)

Hierarchy – Bit < Nibble < Byte < KB < MB < GB < TB < PB < XB < ZB < YB

American Standard Code for Information Interchange (ASCII) is the standard code the computer industry created to represent characters (more than 64 character)

1. 4 bit Nibble

2. 8 bit 1byte

3. 1024 B 1 KB (210)

4. 1024 KB 1 MB (220)

5. 1024 MB 1 GB (230)

6. 1024 GB 1 TB (240)

7. 1024 TB 1 PB (250)

8. 1024 PB 1 XB (260)

9. 1024 XB 1 ZB (270)

10. 1024 ZB 1 YB (280)

Secondary memory – It is a type of computer memory that is not directly accessed by the central processing unit (CPU) of a computer and is usually available as non-volatile memory.

• One of the most common forms of this memory is the hard drive of a computer, which is used to store the operating system (OS) and other programs.

• Other forms of secondary memory include disc drives for compact discs (CDs) or digital versatile discs (DVDs), as well as removable flash memory.

• Hard Drive – a rigid non-removable magnetic disk with a large data storage capacity.

• Floppy disk – A floppy disk, also called a diskette one type of disk storage composed of a disk of thin and flexible magnetic storage medium, sealed in a rectangular plastic carrier lined with fabric that removes dust particles. Floppy disks are read and written by a floppy disk drive (FDD).

• Magnetic Type – Magnetic tape used in recording sound, pictures, or computer data.

• Flash memory – a kind of memory that retains data in the absence of a power supply.

• Optical disk – an electronic data storage medium that can be written to and read using a low-powered laser beam.

• CD-ROM – “Read only” (used for distribution of commercial software, for example) Standard storage capacity is 640MB.

• CD-R (or CD-WORM) – “Write Once, Read Many” times

• CD-RW – rewritable multiple times

• DVD – similar to CD, but with significantly larger storage capacity (4.7 GB)

• Write once read many (WORM) describes a data storage device in which information, once written, cannot be modified.

Motherboard – A motherboard is the main circuit board inside a computer that connects the different parts of a computer together.

It has sockets for the CPU, RAM, and expansion cards (e.g. discrete graphics cards, sound cards, network cards, storage cards etc.) … And it hooks up to hard drives, disc drives, and front panel ports with cables and wires. Also known as mainboard, system board.