n301/cs02digital
n301.tplt
What is a computer?
It is a Universal Information Manipulator
Universal
Is a computer universal?
How is it ‘universal’?
Information
What is information?
- numbers, words and instructions are examples of information
- information is referred to as data
Manipulator
How does the computer manipulate information?
First, let’s talk about ways of storing information
Analog
Webster’s New World dictionary defines analog as “a system of measurement in which a continuously varying values, as sound, temperature, etc. corresponds proportionally to another value, esp. a voltage”
Analog Devices
Mercury thermometer
Radio dial
Clock with a second hand
Slide rule
Analog Information
Is mechanical
Usually offers nearly infinite precision, but limited accuracy.
Digital
Webster defines digital as “…a recording technique in which sounds or images are converted into groups of electronic bits and stored on a magnetic medium…”
Digital Devices
Digital watches
Digital thermometers
Digital Information
Is information stored as a series of numbers
Digital instruments are not as precise as analog counterparts, but are much more accurate
Computers – digital or analog?
We think of computers as digital devices
The digital nature of computers gives them their characteristics – limited precision but extreme accuracy
Information computers understand
They understand numbers – more accurately 0’s and 1’s which is technically on or off in regards to fluctuations in electronic voltages
Binary storage
Any mechanical device that exhibits yes/no behavior is referred to as a switch
A computer is essentially a huge number of switches
Voltages is an analog property, but forcing the circuitry to accept it as one of two values makes the computer a digital system
Binary Example
Light Switch Example
Base 10
Examine the number 642
| 100’s | 10’s | 1’s |
|---|
| 6 * 100 | 4 * 10 | 2 * 1 |
| 600 + | 40 + | 2 |
Example Explained
In the previous example, the value of the digits are based on the powers of 10
6 * 10^2, 4 * 10^1, 2 * 10^0
Remember: any power raised to ^0 is equal to 1.
Computer and Base 2
On and Off, 1 and 0, voltages
Base 2 works just like base 10, but instead of using powers of 10 it uses powers of 2
Binary Example
| Decimal Value | Binary Value | 2^3 | 2^2 | 2^1 | 2^0 |
|---|
| | | 8s | 4s | 2s | 1s |
| 1 | 1 | 0 | 0 | 0 | 1 |
| 2 | 10 | 0 | 0 | 1 | 0 |