Binary Numbers

To be able to convert denary numbers to binary or vice versa, use the table below.

128

64

32

16

8

4

2

1

Floating point representation

​Used to store real numbers in binary using a mantissa and an exponent

ASCII

Text is represented in computer systems using ASCII. Each character is assigned a unique binary code.

Vector graphics

Vector graphics store the attributes of objects in a drawing.

Bitmapped graphics

Bitmapped graphics store the binary colour code of every pixel in an image

Resolution measures the number
of pixels in an image

Inside the processor

The processor is at the centre of every computer system, repeatedly fetching and executing instructions

There are three main parts of the processor

● Control unit
● Registers
● ALU

Memory

Main memory holds all the running
programs and open files on your
computer

Memory is organised into many, many locations

Each location has a unique address so the data or instructions in one location can be fetched

Buses

CPU and RAM are connected by buses to
allow the CPU to fetch

The address bus finds a location in memory in order to read from it or write to it

The data bus transfers instructions and data between memory and processor

Translator programs

When you code in Visual Basic or Python, you use English-like commands such as Repeat, If, Integer, End etc.

The processor does not understand these commands - it only understands binary instructions

So any program has to be translated before it can be run

Translator programs

An interpreter translates and
executes one instruction at a time

It doesn’t save the translated code so has to be translated every time you want to run the program

It identifies errors as soon as the line is translated so is useful for debugging code and removing
mistakes

A compiler translates and executes the entire program in one operation

It saves the translated code so it
doesn’t have to be translated every time you want to run the program

Errors are only identified once all
the code is translated so compilers are best for producing a final version of software for release to customers

Environmental Impact

There are environmental implications of manufacturing and using computer devices.
These can be reduced by
recycling devices
switching off when not in use
using power down settings
using eco mode
reducing screen brghtness

Security Risks

To reduce security risks, we use

Firewalls to filter incoming and outgoing data.
Encryption to encode data whilst being sent so that if intercepted it is unreadable and therefore worthless