Computer memory comes in four main types: primary, secondary, cache, and register. Primary memory, also known as RAM, is the memory that holds data and instructions currently being processed by the CPU. It is volatile and divided into RAM and ROM. RAM is random access and can be written to, while ROM is read-only and helps boot the computer. Secondary memory includes storage devices like hard disks, floppy disks, and tapes, which allow permanent storage of data that can be transferred back to primary memory when needed. Cache memory resides between the CPU and primary memory to speed up access, while register memory is the smallest, fastest memory attached directly to the processor.

1. By
Biswajeet

2. About MEMORY
• A memory just like of human brain. It is used to store
data & instruction. Computer memory is a storage place
in a computer where data is to be processed instructions
required for processing are stored.
• There are mainly 4 types of memory:-
1.Primary memory
2.Secondary memory
3.Cache memory
4.Register memory

3. UNIT
8bits(0&1) 1byte
1024bytes 1kilobyte
1024kb 1megabyte
1024mb 1Gigabytes
1024gb 1Terabytes
1024tb 1Perabytes

4. Primary Memory
• This memory holds those data & instructions on which
computer is currently worked. This memory processed
data & instructions earlier as its known as main memory
of computer.
• Its divided into 2 sub-categories:-
1. RAM
2.ROM

5. RAM(Random Access Memory)
• It access data or information in random basis. A RAM
constitute the internal memory of the C.P.U for storing
data program & program result. Its both read & writable
memory.
• It’s a volatile memory ,the data stored in it is lost.
• These memories are semi-conductor memories. It is
divided into two types:-
1.SRaM
2.DRaM

6. SRaM (Static RaM)
It has long data life time. There is no need to refresh. Its
also faster.
DRaM (Dynamic RaM)
Its used for most system memory because its cheap &
small. It has short data lifetime &also need to refresh
continuously.

7. ROM(Read Only Memory)
It’s the memory from which we can only read but we
cant write on it. It’s non-volatile. It helps the computer
in booting process.
There are 4 types of RoM:-
1. M-RoM (Masked RoM)
2. P-RoM (Programmable RoM)
3. EP-RoM (Erasable Programmable RoM)
4. EEP-RoM (Electrically Erasable Programmable RoM)

8. M-ROM
It’s the very fast RoM device that contain a pre-
programmed set of data & instructions.
P-ROM
Its read only memory that can be modified only once by a
user.
EP-ROM
The EP-RoM can be erased by exposing it to ultraviolet
light for 40 mins.
EEP-ROM
Its programmed & erase electrically. It can be erased & pre-
programmed about 10 thousand times. This process is flexible but
slow.

9. MAGNETIC TAPE – IT IS USED FOR TAKING BACK-UP DATA .THROUGH
SOME MAGNETIC FIELDS
FLOPPY DISK- ITS USED FOR STORING DATA IN A PERMANENT MANNER. IT
STORES ALL THE DATA INTO THE FORM OF TRACKS & SECTORS.
HARD DISK- ITS FIXED INSIDE THE CABINET OF THE CPU. IT MADE UP OFF
MANY METAL PLATTER COATED TO STORED DATA MAGNETICALLY.
MEMORY- IT IS A SMALL STORAGE MEDIUM USED TO STORE DATA SUCH AS
TEXT, PICTURE FOR USE ON SMALL PORTABLE OR REMOTE COMPUTING
DEVICE.
Secondary Memory
This memory is not directly accessed by a computer or processor.
It allows a user to store data that may be instantly & easily transfer
& used by applications.
Ex: Magnetic Tape, Hard disk, Floppy disk & memory.

10. IT’S A VERY HIGH SPEED SEMI-CONDUCTOR
MEMORY WHICH CAN SPEED UP CPU. IT RESIDES
BETWEEN THE CPU & MAIN MEMORY. ITS FASTER
THAN MAIN MEMORY. THE PARTS OF DATA &
PROGRAM ARE TRANSFERRED FROM DISK TO
CACHE MEMORY BY OPERATING SYSTEM. IT
STORES DATA FOR THE TEMPORARY UNITS.
Cache Memory

11. IT’S THE SMALLEST & HIGH-SPEED SEMI
CONDUCTOR MEMORY. ITS VERY COSTLY THAN
ALL. IT CAN STORES ANY INPUT & OUTPUT OF
ANY PROCESS. ITS ATTACHED IN A PROCESSOR,
IT WORKS FOR A PROCESS.
Register Memory