The computer systems we build today feature programmable processing units which interact with a number of devices, each controlled by an I/O controller. A system usually also contains a main memory.
Devices are roughly classified into input devices, output devices and storage devices. Examples of devices are
| Input Devices | Output Devices | Storage Devices |
|---|---|---|
|
Keyboard Mouse Light Pen Joystick Joyswitch Trackball Digitizer Video Camera Voice Recognizer Scanner Data Glove |
Display (CRT, LCD, Plasma...) Printer Plotter Film Recorder Hologram Generator Robot Arm Speaker |
Disk Drive CD or DVD Drive |
Modern computer systems have a layered organization, which each layer either using the services of, or being physically built from, entities on the level directly below it.
| Layer | People | Domain |
|---|---|---|
| Application Programs | Application Programmers | Software |
| System Utility Programs | System Programmers | |
| Operating System | ||
| I/O System (BIOS) | ||
| Computer System | Computer Engineers | Hardware |
| CPU | Computer Architects | |
| Memories, Logic Circuits, Fliop-Flops, Gates | Logic Designers | |
| Transistors, Diodes, Resistors, Power Supplies | Materials Scientists |