J. Stover, CSD-HS

 A computer is an electronic device that is programmed to accept data (input), process it into useful information (output), and store it for future use (storage).  The processing function is under the control of a set of instructions (software); we will explore this later.

 The CPU is the brain of the computer. The CPU consists of electronic circuits that interpret and execute instructions; it communicates with the input, output, and storage devices.  The CPU, with the help of memory, executes instructions in the repetition of machine cycles.

 A computer system has two basic parts ◦ hardware ◦ software.  The equipment associated with a computer system is the hardware.  Computer hardware is responsible for performing four basic functions ◦ Input ◦ Processing ◦ Output ◦ Storage.

 Input devices ◦ send data to the central processing unit ◦ Send instructions to the central processing unit.  Output Central processing unit ◦ executes computer instructions. ◦ Memory holds data and programs temporarily.

 Processing Output devices ◦ make processed data available to the user.  Secondary Storage Secondary storage devices ◦ store data and programs permanently.  In order to function properly, a computer system must have all four types of hardware: input, processing, output, and storage.

 A machine cycle consists of four steps: ◦ The control unit fetches an instruction and data associated with it from memory. ◦ The control unit decodes the instruction. ◦ The arithmetic/logic unit executes the instruction. ◦ The arithmetic/logic unit stores the result in memory.