Computer Basics: Binary System

Data Representation

• Computers are digital, recognizing only two discrete states: on or off.
• They use a binary system with two unique digits: 0 and 1, called bits (short for binary digits).
• The bit is the basic unit of information on a computer.

Bits

• Circuits inside computers work with electricity, reacting to the presence or absence of voltages.
• The presence of a voltage is represented as "1" and the absence of a voltage as "0".
• Each 0 and each 1 is referred to as a "bit".

Bytes

• A byte is eight bits grouped together as a unit.
• It provides enough different combinations of 0s and 1s to represent 256 individual characters.
• These characters include numbers, uppercase and lowercase letters, and punctuation marks.

Decimal Representation

• Decimal number system is base 10, using 10 numbers from 0 to 9.
• It uses a power of 10 representation, with each digit in a decimal number representing a power of 10.

Converting Binary to Decimal

• Binary number system is base 2, using only 0 and 1.
• To convert binary to decimal, each binary digit is multiplied by a power of 2, and the results are added together.

Converting Decimal to Binary

• To convert decimal to binary, find the largest power of 2 that will "fit" into the decimal number, place a 1 in that slot, and subtract the power of 2 from the decimal number.
• Repeat the process until the decimal number is reduced to 0.

Data Representation

• Three popular coding systems to represent data are ASCII, EBCDIC, and Unicode.

ASCII, EBCDIC, and Unicode

• ASCII (American Standard Code for Information Interchange) represents symbols using a 7-bit code.
• EBCDIC (Extended Binary Coded Decimal Interchange Code) is an 8-bit code.
• Unicode is a coding scheme capable of representing all the world's languages.

Converting Letters to Binary and Back

• When a user presses a key on the keyboard, an electronic signal is sent to the system unit.
• The signal is processed and converted to its ASCII binary code.
• The binary code is stored in memory for processing.
• The binary code is converted back to an image and displayed on the output device.

Memory

• Memory is electronic components that store instructions, data, and results.
• It consists of one or more chips on the motherboard or other circuit board.
• Each byte stored in memory has a unique location called an address.

Memory Measurement

• Memory is measured by the number of bytes available for storage.
• KB (Kilobyte) = 1024 bytes.
• MB (Megabyte) = 1 million bytes.
• GB (Gigabyte) = 1 billion bytes.
• TB (Terabyte) = 1 trillion bytes.

Large Memory Units

• Kilo (K) = 2^10 = 1,024 bytes.
• Mega (M) = 2^20 = 1,048,576 bytes.
• Giga (G) = 2^30 = 1,073,741,824 bytes.
• Tera (T) = 2^40 = 1,099,511,627,776 bytes.
• Peta (P) = 2^50 = 1,125,899,906,842,624 bytes.
• Exa (E) = 2^60 = 1,152,921,504,606,846,976 bytes.
• Zetta (Z) = 2^70 = 1,180,591,620,717,411,303,424 bytes.
• Yotta (Y) = 2^80 = 1,208,925,819,614,629,174,706,176 bytes.