Computer Logic

Computer Logic

2-state devices also known as bistable devices  are like a switch on a wall , it can be only one of two possible states : ON or OFF .

However,computers represent the letters of the alphabet by the binary system .Binary is only 2 numbers : 1 and 2 . With 3 bits we represent 8 characters and with 4 bits we represent 16 characters.

There are also number conversions . You do them by using the LSB ( least significant figure and the MSB ( most significant figure) . When studiying computer studies you should know how to convert these : 

• converting binary to decimal
• converting decimal to binary
• converting binary to hexa decimal
• converting hexa decimal to binary
• converting decimal to hexa decimal
• converitng hexa decimal to decimal

In a computer we use the representation of characters by the ascii code and the unicode.The ascii code is an 8 bit device and can represent 256 characters. It also has it's limitations.

Ascii stands for : - American Standard Code for Information Interchange.

A bit = 0 or 1 

Byte = 8 bits

Kilobyte = 1024 bytes

Megabyte = 1024 kilobytes

Gigabyte = 1024 megabytes

Terabyte = 1024 gigabytes

Analogue and Digital data

An analogue device is one which data is represented by some quantity which is continuously changing , Hence a digital device shows data at discrete intervals.

A modem ( MODulator & DEModulator ) = the purpose is to convert between the analogue signals and the telephone cables and the digital signals used by a computer.

Either than a modem ,network cards and sound cards can also be used.

From analogue to digital is <ADC> & from digital to analogue is <DAC>