Memory: memory is a storage area in the system.which usually store data and programs.almost every system needs a memory unit to store instructions of programs.
Classification of Memory:
Random Acess Memory (RAM):
It gets the word "random" because information can be accessed in non-sequential order. Though the
data itself is stored together, it could be anywhere in the "container" or amount of RAM available.
The microprocessor can Read the data from the RAM quickly faster than even from ROM. The microprocessor can write new data to the RAM quickly, erasing the old data in the RAM. The RAM forgets its data if the power is turned off.
Classification:
RAM is classified into two types Static RAM and Dynamic RAM.
Static RAM:
Static RAM retains data bits in its memory as long as power is being supplied. it remembers its data without any assistance from other parts of the circuit. the parts look like ROM parts expect that they have a write enable signal. it is a construction of circuits similar to D-flip flop. it is expensive and faster but generates more heat and consumes more power. it acts as a cache.
Dynamic RAM:
Dynamic RAM depends on being read once in a while otherwise it forgets its data. Systems employing dynamic RAM use a circuit called dynamic RAM refresh. it is a construction of tiny capacitors. it is inexpensive and uses less power but it is slower.it acts as main memory.
Comparison Table:
Read Only Memory (ROM):
The memory from which we can only read but cannot write on it. This type of memory is non-volatile. The information is stored permanently in such memories during manufacture. A ROM stores such instructions that are required to start a computer.
I hope this article was successful in explaining you the basics of Memory.
You can write to me at codingallrounders@gmail.com
Programmable Read Only Memory (PROM):
It is Empty of data when manufactured but Maybe permanently programmed by the user. The device programmer writes data to the device one word at a time by applying an electrical charge to the input pins of the chip. Once a PROM has been programmed in this way, its contents can never be
changed. If the code or data stored in the PROM must be changed, the current device must be discarded. As a result, PROMs are also known as one-time programmable (OTP) devices.
Erasable Programmable Read Only Memory (EPROM):
It can be programmed, erased and reprogrammed. the EPROM chip has a small window on top allowing it to be erased by shining ultra-violet light on it after reprogramming the window is covered to prevent new contents being erased. the access time is around 45 – 90 nanoseconds.
Electrically Erasable Programmable Read Only Memory (EEPROM):
It is Reprogrammed electrically without using ultraviolet light. it must be removed from the computer and placed in a special machine to do this. the access times between 45 and 200 nanoseconds.
Flash ROM:
It is Similar to EEPROM however it can be reprogrammed while still on the computer. it is easier to upgrade programs stored in Flash ROM. it is used to store programs in devices e.g. modems. the access time is around 45 – 90 nanoseconds. it stores information in an array of memory cells.
You can write to me at codingallrounders@gmail.com
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