Memory Units and Secondary Memory for Competitive Exams

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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.

As showing in images is a types of Secondary Memory.

Secondary Memory

As showing in images is a types of Secondary 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.

This diagram shows types of storage memory

Diagram Shows Storage Memory

This diagram shows types of storage memory

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.

This image shows motherboard

Image of Motherboard

This image shows motherboard