 A computer is an electronic device that receives data (input), processes data, stores data, and produces a result (output).  It performs only three operations  Arithmetic operations (adding, subtracting, dividing, and multiplying.)  Logical comparison values (equal to, greater than)  Storage and retrieval operations  Big deal..? Why and how do you use computers and which kinds do you use?

TypeSizePowerPurpose SupercomputersLargestFastest processing speeds compared to other computers Cost can be several million dollars For corporations with lots of data to be processed Mainframe computers LargeLess powerful than supercomputers but large compared to personal computers Can cost hundreds of thousands of dollars Performs centralized processing tasks for many users MinicomputersLarger than microcomputers but smaller than mainframe computers Same as microcomputers Used for companies with many users and large amounts of data and can run on any computer hardware Microcomputers and notebook computers Fits on a desktopNot meant for large amount of data Writing papers, tracking finances, playing games, connecting to the Internet. PDA’s, Cell phones, calculators, interactive books, digital cameras, game systems are accepted as they make everyday tasks easier to accomplish.

 Role: The CPU also called microprocessor, or brain of the computer, contains millions of switches and pathways to help the computer make decisions. The switches control the flow of electricity as it travels across the pathways. Computer programs are special instructions written to tell the computer which switches to turn on or off.  Speed: deciding factor on which computer to purchase. The system clock is an electronic pulse used to synchronize the processing and determines the speed of the processor, measured in megahertz. The higher MHz the faster the computer.

 Computers only understand machine language, or binary, which is ones and zeros.  Through the pathways and by turning switches on and off the CPU processes ones and zeros  When electricity is present it represents a one. The absence of electricity represents a zero.  Coding Systems such as American Standard Code for Information Interchange (ASCII) determines which combination of zeros and ones represents the letter A or the number 1.  Each one or zero is a bit, and eight bits or combinations of ones and zeros represents a byte.

 RAM – (random access memory) often referred to as main memory is the data, information, and program instructions temporarily stored on a RAM chip. If there is a power loss this is the information lost. The amount of Ram can help increase how fast the computer processes data.  ROM – (read only memory) stores specific instructions needed for computer operations. The computer can read from a ROM chip but cannon write or store data on this chip.

 Secondary storage devices are used when you want to store a file or information permanently  Computer’s hard disk drive  Floppy disk  CD-ROM  Thumb drive

 A network connects one computer to other computers and peripheral devices  Allows computers to share:  Data – special group projects, databases, etc.  Hardware – printers or scanners  Software – instead of purchasing programs for each individual computer, a site license can be purchased for the number of users and it is less expensive  Files – collaborative, allows users to work together