Bits & Bytes

[Class-A]

Computers only work with binary numbers. A binary number, or bit for short, is the smallest unit of information that is used by a computer and consists of one of two different characters, a 0 (zero) or a 1 (one). A 0 would refer to off or false or no, while a 1 would refer to on or true or yes. A simplified example of the use of a bit would be when the computer is booted up, it sends out a signal to the printer connected to the computer to see if it is ready to accept documents. Assuming that the printer is turned on and isn't ready yet, it would respond by sending back a 0 indicating no, I'm not ready. If the printer is ready, it would respond by sending back a 1 indicating yes, I am ready. When you see the speed rating of a communications device, such as a serial port or a modem, the speed will be listed in bps or bits per second. A modem that has a rating of 56K bps (since K refers to thousand, that is 56,000 bps) would have the capability to sending or receiving 56,000 0s and/or 1s in one second.

Since sending out information 1 bit at a time can be rather time consuming for the computer, information is sent as a package of data or instructions called a byte. A byte is made up of 8 bits of information, such as 00000000 or 10101010. Most of a computer's specifications are represented in terms of bytes, such as the computer's memory capacity or the size of a disk drive.


Term Symbol Value
bit b 0 or 1
byte B 8 bits
kilobit Kb 1,024 bits
kilobyte KB 1,024 bytes
megabit Mb 1,048,576 bits
megabyte MB 1,048,576 bytes
gigabit Gb 1,073,741,824 bits
gigabyte GB 1,073,741,824 bytes
terabit Tb 1,099,511,627,776 bits
terabyte TB 1,099,511,627,776 bytes

[Singachea]

I think it might confuse the readers if we try to explain that bit is 0 or 1. Actually, bit is a digit in base 2. A digit in Decimal containing 10 possible values: 0-9. Likewise, a digit in binary also contains 2 possible values: 0 and 1. Why does computer understand only binary? It's simple to explain something like on and off. To see details, we need to realize some basic functions of the electronic devices such as transistors, logic gates, ...

Byte is an 8-bit size, and Word is 2 bytes. Normally we use byte size because of ASCII codes for English characters, and that's why in C programming language it takes 1 byte for character, but it takes 2 bytes in Java as Java uses Unicode.