Binary
The denary number system (also known as decimal) uses 10 symbols (0-9) to represent numbers. It is a base-10 number system. Humans use it because we have 10 fingers. Computers don’t have fingers, they have circuits. These circuits can be in one of two states, on or off. So they use a base-2 number system. The off state of a circuit is represented as a 0 and the on state is represented as a 1.
Binary to Denary
Denary to Binary
Representing Text
Text is represented on computers by assigning a unique binary number to each character. For example, 1000001 is used to represent the letter A. This system is known as ASCII (American Standard Code for Information Interchange). Here are the ASCII codes for capital letters:
| ASCII Code | Letter |
|---|---|
01000001 |
A |
01000010 |
B |
01000011 |
C |
01000100 |
D |
01000101 |
E |
01000110 |
F |
01000111 |
G |
01001000 |
H |
01001001 |
I |
01001010 |
J |
01001011 |
K |
01001100 |
L |
01001101 |
M |
| ASCII Code | Letter |
|---|---|
01001110 |
N |
01001111 |
O |
01010000 |
P |
01010001 |
Q |
01010010 |
R |
01010011 |
S |
01010100 |
T |
01010101 |
U |
01010110 |
V |
01010111 |
W |
01011000 |
X |
01011001 |
Y |
01011010 |
Z |
Representing Sound
Sound is analogue, a continuous waveform. A computer cannot store analogue information, so it captures the amplitude of the wave at key points; these are known as samples. The more samples the computer captures per second, the higher the sound quality.
Representing Images
Images are stored on computers using lots of tiny dots called pixels. Each of these is represented by a binary number that tells the computer what colour it is. The number of pixels contained in the picture is known as the resolution; the higher the resolution, the higher the image quality.