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Computers |
What is a Computer?
Device capable of performing computations and making logical decisions.
Computers process data under the control of sets of instructions called computer programs.
Hardware
Various devices comprising a computer.
Keyboard, screen, mouse, disks, memory, CD-ROM, and processing units are all examples of hardware.
Software
Programs that run on a computer.
Computer Organization |
Input unit |
Obtains information from input devices (keyboard, mouse) |
Output unit |
Outputs information (to screen, to printer, to control other devices) |
Memory unit |
Rapid access, low capacity, stores input information (RAM) |
Arithmetic and logic unit (ALU) |
Performs arithmetic calculations and logic decisions |
Central processing unit (CPU) |
Supervises and coordinates the other sections of the computer |
Secondary storage unit |
Cheap, long-term, high-capacity storage, Stores inactive programs ( HardDisk) |
Evolution of Operating Systems |
Batch processing |
Do only one job or task at a time |
Operating systems |
Manage transitions between jobs.Increased throughput (Amount of work computers process). |
Multiprogramming |
Computer resources are shared by many jobs or tasks. |
Timesharing |
Computer runs a small portion of one user’s job then moves on to service the next user. |
Computing |
Personal computers |
Economical enough for individual (Apple 1977 , IBM 1981 ) |
Distributed computing |
Computing distributed over networks |
Client/server computing |
Sharing of information across computer networks between file servers and clients (personal computers) |