- Due to the fact that:
- The computer memory consists
of (many many) switches and
and a
switch can only
record one
of
2 different values:
Switch is off ≡ 0 Switch is on ≡ 1
the computer system will use the binary number system to represent numbers
In fact:
- A computer can only store binary numbers !!!
To be really clear: the only things that exist inside a computer are binary numbers !!!!
- The computer memory consists
of (many many) switches and
and a
switch can only
record one
of
2 different values:
- $64,000 question:
- How can you store other kinds of information (like letters) ???
Answer: use codes !!!
(I.e.: just pretend !!!)
- Code:
- A code is an agreement used to represent information
There are many different codes used in the computer to represent different kinds of information !!!
- We design a
code to
represent
each type of
information stored inside the
computer:
- There is a code (called "2's complement code") to represent integer numbers
- There is a code (called "ASCII code") to represent characters in words
- There is a code to represent floating point numbers
- There is a code to represent boolean values
- A commonly used type of
codes are
very "agreement" codes:
- For example,
when children play a secret game,
they may designed a
secret code used
among themselves...
The children may agree that:
0 means "I can't play now" 1 means "I can play now"And use this code to exchange secret messages with each other.
A similar type of code is used to represent boolean values inside the computer:
0 means false 1 means true
- For example,
when children play a secret game,
they may designed a
secret code used
among themselves...
- Other codes are
mathematical codes
used to
simplify computations
(= arithmetic operations)
performed by the computer
- Later in the course, you will learn:
- How to represent
characters using
numbers
(= ASCII encoding)
- How to represent signed value using binary numbers that make addition/subtraction easier to do (= 2'c complement code)
- How to represent
characters using
numbers
(= ASCII encoding)