Computing Revision Cards

Computing cycle
When a CPU performs a task, it fetches the instructions from memory.
Then it decodes the instruction to find out what processing to do.
Finally, it executes the instruction.
The processor is the brains of a computer and does all of the calculations.
The first computers:
Colossus was one of the first computers constructed.
In its day it was considered to be very fast, it could read 5 thousand characters per second!
It was designed at Bletchley Park, by a team of men and women led by Alan Turing.
It was built during the Second World War to break the German codes that were sent out to their
The German code machine was called Enigma.
Computers use binary
Computers are electronic devices that use just two data values, 0 and 1.
They can tell the difference between a high and low voltage, so we use 1 to high and 0 to represent
Using two values to represent data is known as binary or base 2.
All data in a computer must be in binary, so anything that is to be processed or transferred between
computers must first be converted to a series of 1s and 0s.
Problem solving :
Decomposition - Break the problem down into smaller more manageable tasks. Most problems can
be decomposed in this way
Abstraction - Strip away the fine details of the problem so that you can identify common patterns
that will help solve the problem.
Pattern identification - looking for identifiable patterns in raw data using data analysis.
Hypothesis testing (giving a proposed explanation for something) - Using scientific observation and
investigation to see if your hypothesis is good.
Selection - Possible courses of action that will be selected as a result of certain conditions being met.
Create an algorithm (a set of instructions that have to be followed in a certain order).
Make the algorithm more efficient by use of repetition and iteration.
Execute the program (this means run through the program) on paper first to see if it will work (this is
called a dry run).
Generalisation - use the concepts from the solution of a particular problem to solve other problems
that have similar features.
The parts of a URL (Uniform Resource Locator) for a webpage:
transfer protocol
world-wide web
(web pages)
Domain Name
Domain Suffix
File path for the
web page
The web can be best described as servers connected together to supply information requested by
browsers from around the world.
It started as a US government network called APANET and is one of the world's largest artefacts.
It consists of trillions of web pages created in the HTML language. The web allows easy sharing of
knowledge around the world
Your experience of programming:
You have used Scratch which is a programming language that has a drag and drop interface
You may have used LOGO and Python which are text-based programming languages where you
write code in the form of text-based instructions