OCR J277/01 – 1.2 Memory and Storage

Posted on by Administrator Posted in J277 - Computer Science GCSE (OCR)
1.2 Memory and Storage - Overview / Checklist
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

Recommended Resources

1.2.1 Primary storage (Memory)
BBC Bitesize – Primary Memory
1.2.2 Secondary storage
BBC Bitesize – Secondary Storage
1.2.3 Units

Understanding Binary Data

Binary data is made of 0s and 1s. These binary digits are called bits are used to convert numbers into digital/binary data.


101 Binary Watch

A binary watch uses 18 LEDs to give the HH:MM:SS time using three binary numbers each consisting of 6 bits. The following diagram can help you understand how to work out the time displayed on a binary watch: Using the … Continue reading


Storage Units Conversions – Quiz

The following diagram is a quick recap of the main storage units used to estimate the size of a file or the storage capacity of a storing device. Take the Quiz! (open full screen) Did you like this challenge? Click … Continue reading


1.2.4 Data storage

Binary Logic Activities

Access a range of activities about binary logic, logic gates, truth tables and Karnaugh maps: Did you like this challenge? Click on a star to rate it! Submit Rating Average rating 4.5 / 5. Vote count: 158 No votes so … Continue reading


Understanding Bitmap Pictures

In this blog post we are investigating what are bitmap pictures and how they are stored on a computer using binary code. Bitmap Pictures? Bitmap pictures (also called raster graphics) are computer graphics made of pixels of different colours. Pictures … Continue reading


Sampling Sound

Sampling is a method of converting an analogue audio signal into a digital signal. While sampling a sound wave, the computer takes measurements of this sound wave at a regular interval called sampling interval. Each measurement is then saved as … Continue reading

Digital Data – Terminology File Size Calculations Q&A File Size Calculations – Python Challenge ASCII Quiz – Python Challenge
1.2.5 Compression
Lossless Compression Poem Decoding Challenge

Further Reading…

Extra Resources
Input / Storage / Output Devices – Quiz Computer Hardware Crosswords Computer Hardware Acronyms Hardware Contest

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