GCSE Computing
Binary Units
Candidates should be able to:
OCR: 2.1.4 (b) understand that data needs to be converted into a
binary format to be processed by a computer.
AQA: 3.1.10 understand that computers use the binary alphabet to
represent all data and instructions
Binary numbers are fundamental to the way that all modern computers work. They are used to
represent any data stored within a computer system. A clear understanding of binary numbers is
therefore essential for any student of Computing.
Most students will not have met binary numbers before and will need to spend some time getting used
to them. It is vital not to rush the early stages of this work; students can all too easily develop a mental
block.
Using only 0 and 1 makes it easier to design the electronic circuits that the computers will use. This is
because, if the computer wants to check a value in any part of the circuit, it only needs to detect
whether or not there is any electricity. If there is electricity, the value is 1, if there is no electricity, the
value is 0.
Why Binary Game
The activity helps students to understand why binary representation is used by computers – it is a
much more reliable way of storing and transmitting data than denary representation.
http://gcsecomputing.net/wp-content/uploads/2012/01/OCR%20A451%202.1.4%20Units%20%20Why%20Binary.pps
Candidates should be able to:
OCR: 2.1.4 (a) define the terms bit, nibble, byte, kilobyte, megabyte,
gigabyte, terabyte
AQA: 3.1.10 understand the terms bit, nibble, byte, kilobyte,
megabyte, gigabyte and terabyte
If a switch is on, it can represent the number 1. If it is off, it represents 0. These states can also be
interpreted as TRUE or FALSE. If you have enough switches, you can store all sorts of data. You
could ask a question such as ‘will you give me some money?’ and you can get an answer in binary
digits:
0 = NO
1 = YES
This is making use of just 1 bit of data. Add another bit and you can say more:
00 = NO
10 = MAYBE
01 = YES
11 = NEXT WEEK
The more binary digits you have, the more information you can store and process. Most computers
store bits of data in memory in groups of eight. Eight bits stored at one location is called a byte.
Sometimes it is useful to work on just half a byte. Half a byte is called a nibble.
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GCSE Computing Notes © gcsecomputing.net
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GCSE Computing
Binary Units
byte
A bit (binary digit) is the basic unit of information in computing.
A nibble consists of 4 bits. A nibble corresponds to a single hexadecimal digit.
A byte consists of eight bits. A byte was the number of bits used to encode a single character of text
in a computer and for this reason it is the basic addressable element in many computer architectures.
A kilobyte (kB) is 1024 bytes. The reasoning behind it being 1024 and not 1000 is that we use powers
of 2, not 10, to represent binary numbers. (NOTE: the small k on kB). 1kB of memory could store
roughly one full A4 page of text.
A megabyte (MB) is 1024 kB or 220. 1 MB is about the amount of data that is needed to store a full
screen image, 1 minute of MP3 music, 6 seconds of uncompressed CD audio or a typical book.
A gigabyte (GB) is 1024 megabytes or 230 bytes. 1 GB is enough data for one hour of standard
video, 7 minutes of high definition video or 114 minutes of uncompressed CD quality audio. A duallayered Blu-ray disc can hold about 50 GB.
A terabyte (TB) is 1024 gigabytes or 240 bytes. This is a difficult amount to comprehend, but Yahoo!®
groups have about 40 terabytes of stored data. The first 1TB hard drive was produced in 2007.
Ancestry.com claims approximately 600 TB of genealogical data with the inclusion of US Census data
from 1790 to 1930. Released in 2009, the 3D animated film Monsters vs. Aliens used 100 TB of
storage during development. The first 20 years’ worth of observations by the Hubble Space
Telescope has amassed more than 45 terabytes of data
Wikipedia
There are lots of interesting usage examples about storage and information on multiples of bytes up
to yobibyte (2^80 bytes).
Posters
This is a good opportunity for students to produce some posters of the pyramid of units.
Teaching Binary using the Socratic Method
http://www.garlikov.com/Soc_Meth.html
Binary Numbers Magic Trick
http://www.mathmaniacs.org/lessons/01-binary/Magic_Trick/
Secret Binary Numbers
http://www.mathmaniacs.org/lessons/01-binary/SecretNumbers.html
Count To 1023 On Your Fingers
http://www.mathmaniacs.org/lessons/01-binary/count_to_1023.html
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