(1)- The system unit includes the chassis, microprocessor, main memory, bus, and ports, but does not include the keyboard or monitor, or any peripheral devices.
- A system unit is sometimes called a box or main unit.
How to Assemble a System unit.wmv :(2)
ROM(Read-Only Memory)
- PROM (Programmable Read-Only Memory)
- EPROM (Erasable Programmable Read-Only Memory)
- EEPROM (Electrically Erasable Programmable Read-Only Memory)
1. PROM (Programmable Read-Only Memory)
- The process is known as burning the PROM.
- This device uses high voltages to permanently destroy or create internal links (fuses or anti-fuses) within the chip.
- It is a permanent storage device that becomes a read-only memory after it is written once by the customer rather than by the chip manufacturer.
- They are frequently seen in video game consoles, or such products as electronic dictionaries, where PROMs for different languages can be substituted.
2. EPROM (Erasable Programmable Read-Only Memory)
- A type of computer memory chip that retains its data when its power supply is switched off & it is non-volatile.
- It can be erased only by exposing it to strong ultraviolet light & normally used in electronic circuits.
- EPROMs are easily recognizable by the transparent fused quartz window in the top of the package, through which the silicon chip can be seen, and which permits UV light during erasing.
3. EEPROM (Electrically Erasable Programmable Read-Only Memory)
- EEPROM-chip can be erased, either within a computer or externally, by electric power.
- There are two types of EEPROM: Electrically alterable read-only memory (EAROM) and Flash memory (or simply flash).
- It is a technology that is primarily used in memory cards and USB flash drives for general storage and transfer of data between computers and other digital products.
(3)Citation:
-(1)http://www.webopedia.com/TERM/S/system_unit.html
-(2)http://www.youtube.com/watch?v=n6umAYBUYHE&feature=related
-(3)http://sunwayiconz.wordpress.com/
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