August 25, 2010 notes

On/Off

1/0

Computer systems are constructed of digital electronics. That means the their electronic circuits can exist in only one of two states, on or off. Most computer electronics use voltage levels to indicate their present state. For example, a transistor with five volts would be considered "on|" while a transistor with no voltage would be considered "off". Not all computer hardware uses voltage hardware CD-ROM zx's, for example use

microscopc dark spots on the surface of the disk to indicate "off", while the ordinary shiny surface is considered "on". Hard disks use magnetism, while computer memory uses electric charges stored in tiny capacitors to indicate "on" or "off".

Information is digital. Digital means that its made up of small, countable digits called digits.

A computers cant digest information unless it is a a bit/binary degit

*Bits as Numbers

         ^Binary Number System

                    -Binary number denotes all numbers with combinaions of two digits.

                    -Decimal numbers are automatically converted in binary number and vice versa.

                    -Binary number processing is completely hidden from the user.


Bits as Codes
*ASCII
         -The most widely used code
         -An abbreviation of American Standard Code for Information Interchange

*Unicode
         -A coding scheme that supports 65,000 unique characters


Bits as Instructions in Programs
* Programs are stored as collections of bits
         -Program instructions are represented in binary notation through the use of codes


Bits, Bytes, and Buzzwords
*Bit-related terminology
          Byte = 8 bits
          Kilobyte(KB) = 1 thousand bytes
          Megabytes(MB) = 1 million bytes
          Gigabytes(GB) = 1 billion bytes
          Terabytes (TB) = 1 trillion bytes


Green Computing
  The manufacture of hardware and software that can have an impact on the environment
         - Energy Star equipment
         - Notebook/Laptop & a solar battery
         - Energy saving features
         - Turn off the computer when you are away
         - Screen Savers don't save energy
         - Print only once
         - Recycle waste