The function of MU is to store information, It stores programs, data, results or any other kind of informations. It has mainly 2 types of memory.
1)Primary(Main) Memory
2)Secondary Memory
1)Primary(Main) Memory :
It is the fastest memory of computer. It stores all the necessary informations required to execute a program. CPU directly addresses the primary memory. Semiconductors are used to construct primary memory of a computer called RAM(Random Access Memory)
RAM(Random Access Memory) : It is a computer memmory that can be accessed without touching the preceding bytes. THere are 2 types f RAM(Dynamic RAM Static RAM)
Dynamic RAM needs to be refreshed thousand of times per second. Static RAM does not need to be refreshed which akes it faster, but more expensice than DRAM.
Both RAM are volatile, means that the data content in the RAM is lost when power is turned off.
ROM(Read Only Memory) : It is a memory on which data has been pre=record. Once data has write onto a ROM chip, it cant be changed and it can only be read. Unlike primary memory, ROM retains its contents even when the computer is turned off.
It is referred to be a non-volatile memory where as RAM is volatile. There are :
a)Programmable Read Only Memory(PROM),
b)Erasable Programmable Read Only Memory(EPROM),
c)Electrically Erasable Programmable Read Only Memory(EEPROM).
a)Programmable Read Only Memory(PROM) : PROM is a memory chip on which data can be written only once and once written t can not be erased.
b)Erasable Programmable Read Only Memory(EPROM) : EPROM is a special type of memory that retaons its content until it is exposed to uv rays.
c)Electrically Erasable Programmable Read Only Memory(EEPROM) : EEPROM is a special type of memory of PROM that can be erased by exposing it to an electrical charge.
