input and output
in computing input/output or I/o (or informally, io or IO) is the communication between an information processing system (such as a computer) and the outside world, possibly a human or another information processing system. inputs are the signals or data received by the system and outputs are the signals or data sent from it. The term can also be used as part of an action; to "perform I/O" is to perform
A computer case also known as a computer chassis, tower, system unit,cabinet, base unit or simply case and sometimes incorrectly referred to as the "CPU" or "hard drive", is the enclosure that contains most of the components of a computer (usually excluding the display, keyboard and mouse).
Cases are usually constructed from steel (often SECC — Steel, electrogalvanized, cold-rolled, coil) or aluminium. Plastic is sometimes used, and other materials such asglass, wood and even Lego blocks have appeared in home-built cases.
ram and rom
Read-only memory (ROM) is a class of storage medium used in computers and other electronic devices. Data stored in ROM can only be modified slowly, with difficulty, or not at all, so it is mainly used to distribute firmware (software that is very closely tied to specific hardware, and unlikely to need frequent updates).
Strictly, read-only memory refers to memory that is hard-wired, such asdiode matrix and the later mask ROM. Although discrete circuits can be altered (in principle), Integrated Circuits (ICs) cannot and are useless if the data is bad. The fact that such memory can never be changed is a large drawback; more recently, ROM commonly refers to memory that is read-only in normal operation, while reserving the fact of some possible way to change it.