• Computer recognize only two discrete state: on and off

-because computers are electronic devices powered by electricity, which

also has only two state on and off.

• Digit 0 represents the electronic state of off

• Digit 1 represents the electronic state of on

• Binary system – a number system that has just to unique digits 0 and 1 called bits.

• Bit – smallest unit of data the computer can process.

• Byte – grouped by 8 bits together

- provides enough different combination of 0s and 1s to represent 256

individual characters. (numbers, uppercase & lowercase letters of

alphabet, punctuation marks and others)

• Coding scheme – combination of 0s and 1s that represent characters are

defined by patterns.

• ASCII (American Standard Code for Information Interchange)

- most widely used coding scheme to represent data

• ASCII coding scheme is sufficient for English and Western European languages but not large enough for Asian and other languages that use different alphabets.

• Unicode – 16-bit coding scheme that has the capacity of representing more than 65,000 characters and symbols.

- implement in several operating system such as Window, Mac OS and

Linux.

• Unicode-enable programming languages and software include Java, XML, Microsoft Office and Oracle

How characters are converted?

1. Press a key on keyboard.

2. Chip in the keyboard converts the key’s electronic signal into a special code that is sent to the system unit.

3. System unit converts the code into ASCII binary code and store it in memory for processing.

4. Every character is converted to its corresponding byte and process the data.

5. Software converts the byte into number, letters or other character that recognize by human is then displayed on screen.