January 17, 2011

 Read Only Memory (ROM)




Stands for Read Only Memory. It is built into the computer. ROM is non-volatile and only permits the user to read data. ROM performs the read operation only does not have a write capability which means we cannot store any new information into ROM. An example of a BIOS (Basic Input Output Systems) chip are permanently loaded during the manufacturing time. ROM holds instructions for starting up the computer. The data does not get erased when the power is switched off.

ROM is 4 Types :

(a) ROM (Read Only Memory) :
This is stored at the time of manufacture of the chips

(b) Programmable Read Only Memory (PROM):
PROM is non-volatile. Once the chip has been programme, the recorded information can't be changed. i.e. the PROM becomes ROM and the storaged information can only be read.

(c) Erasable  Programmable Read Only Memory (EPROM):
It is similar to PROM except that erasing is possible by exposing to ultraviolet light.

(d) Electrically Erasable  Programmable Read Only Memory (EEPROM):
A recently developed type of memory that can be programmed and erased inside a computer system using an electrically signals. EEPROM used in many electronic devices.

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