J277 OCR Computer Science Unit 1.2 Revision Sheets / Practice Questions

NEW J277 SPECIFICATION

Here you will find easy to follow revision sheets which will help your students to recap the topic:

1.2 Storage and Memory which includes:

• 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:
  o Optical
  o Magnetic
  o 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:
  o Capacity
  o Speed
  o Portability
  o Durability
  o Reliability
  o Cost

¨ The units of data storage:
o Bit
o Nibble (4 bits)
o Byte (8 bits)
o Kilobyte (1,000 bytes or 1 KB)
o Megabyte (1,000 KB)
o Gigabyte (1,000 MB)
o Terabyte (1,000 GB)
o 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 binary integers to their 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.:
o ASCII
o Unicode
Images
¨ How an image is represented as a series of pixels, represented in
binary
¨ Metadata
¨ The effect of colour depth and resolution on:
o The quality of the image
o 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:
o The playback quality
o The size of a sound file

¨ The need for compression
¨ Types of compression:
o Lossy
o Lossless

The revision sheets include over 50 exam questions at the end of each topic to help the students recap their revision and apply it to a question.

Enjoy!