Vocabulary Electronic pulses Transistors Decimal numbers Binary numbers ASCII text code Unicode Bit Byte Kilobyte (KB) Megabyte (MB) Gigabyte (GB) Terabyte (TB)

Current Electricity: Regular current electricity: A continuous unbroken flow of electricity: “hummm…” Electric appliances use current electricity –including computers. But computers turn current electricity into electronic pulses.

Electronic Pulses: Electronic pulses: Separate pulses of electric charge: “Beep beep beep …” Each pulse represents one bit: a 0 or a 1. Eight pulses traveling through the transistors of a computer = 1 byte = 1 letter or other piece of data.

Transistors Microscopic electronic “on/off” switches, that make up the circuits inside a computer’s CPU, RAM, other hardware. When an electronic pulse passes through a transistor, it is set to “on” (1) or “off” (0). 8 switches = 8 bits = 1 byte. This is how computers code information.

Bits We use the decimal number system, with 10 digits: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9. Computers use the binary number system, with just 2 digits: 0 and 1. A bit is a single binary digit (0 or 1).

Bytes A set of 8 bits grouped together = 1 byte. Each byte codes for 1 letter, or number, or other character, or 1 sound or color. Example: 01000011 = C 01000001 = A 01010100 = T 28 = 256 possible combinations of 0, 1

Multiples of Bytes Because each byte codes for just 1 letter (or number…), even a small document can be many thousands of bytes in file size. A digital photograph is millions of bytes large. Therefore, it is helpful to have units of large numbers of bytes: Kilobyte (KB), megabyte (MB), gigabyte (GB), and terabyte (TB).

Multiples of Bytes Abbrev. Name Approx. # of bytes KB Kilobyte 1,000 (thousand) MB Megabyte 1,000,000 (million) GB Gigabyte 1,000,000,000 (billion) TB Terabyte 1,000,000,000,000 (trillion)

Text Codes Computers use specific codes for what information each byte represents. ASCII (pronounced “as-key”) = The standard code of 8-bit bytes (as in the C A T example). Unicode = a worldwide code, used on the Internet and elsewhere. By using 2 bytes (16 bits), Unicode has over 65,500 different characters and symbols!