OCR GCSE (J277) SLR 1.2 – Memory and Storage

It includes:

• Student Learning Record Workbook (for use by students)
• Student Learning Record Answers (for use by teachers)
• End of Topic test and answers
• Lesson PowerPoint’s for every lesson
• Any associated answers or references sheets for class activities

This topic covers:

1.2.1 Primary storage (Memory)

• 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

1.2.2 Secondary storage

• 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

1.2.3 Units

• The units of data storage:
• Bit
• Nibble (4 bits)
• Byte (8 bits)
• Kilobyte (1,000 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

1.2.4 Data storage

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.:
• 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

1.2.5 Compression

• The need for compression
• Types of compression:
• Lossy
• Lossless