Current Electricity: 1.Regular current electricity: A continuous unbroken flow of electricity: Electric appliances use current electricity –including computers. But computers turn current electricity into electronic pulses. “hummm…”
Electronic Pulses: 1.Electronic pulses: Separate pulses of electric charge: 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. “Beep beep beep …”
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: =C =A =T 2 8 = 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. NameApprox. # of bytes KBKilobyte1,000 (thousand) MBMegabyte1,000,000 (million) GBGigabyte1,000,000,000 (billion) TBTerabyte1,000,000,000,000 (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!