Paper1:
Computer Systems.

1.2 Memory and Storage

  • The need for primary storage

  • The difference between RAM and ROM

  • The purpose of ROM in a computer system

  • The purpose of RAM in a computer system

  • Virtual memory

  • The need for secondary storage

  • Common types of storage:

    • Optical

    • Magnetic

    • Solid state

  • Suitable storage devices and storage media for a given application

  • The advantages and disadvantages of different storage devices and storage media relating to these characteristics:

    • Capacity

    • Speed

    • Portability

    • Durability

    • Reliability

    • Cost

  • The units of data storage:

    • Bit

    • Nibble (4 bits)

    • Byte (8 bits)

    • Kilobyte (1000 bytes or 1 KB)

    • Megabyte (1,000 KB)

    • Gigabyte (1,000 MB)

    • Terabyte (1,000 GB)

    • Petabyte (1,000 TB)

  • How data needs to be converted into a binary format to be processed by a computer.

  • Data capacity and calculation of data capacity requirements

Numbers

  • How to convert positive denary whole numbers to binary numbers (up to and including 8 bits) and vice versa

  • How to add two binary integers together (up to and including 8 bits) and explain overflow errors which may occur

  • How to convert positive denary whole numbers into 2-digit hexadecimal numbers and vice versa

  • How to convert from binary to hexadecimal equivalents and vice versa

  • Binary shifts

Characters

  • The use of binary codes to represent characters

  • The term ‘character-set’

  • The relationship between the number of bits per character in a character set, and the number of characters which can be represented, e.g.:

    • ASCII

    • Unicode

Images

  • How an image is represented as a series of pixels, represented in binary

  • Metadata

  • The effect of colour depth and resolution on:

    • The quality of the image

    • The size of an image file

Sound

  • How sound can be sampled and stored in digital form

  • The effect of sample rate, duration and bit depth on:

    • The playback quality

    • The size of a sound file

    • The need for compression

    • Types of compression:

      • Lossy

      • Lossless