Different types of Computer Memory & its Classification.

1. PREPARED BY-ARUNA.J.VASAVA

2. What is Memory?
 In computing, memory refers to a device
that is used to store information for
immediate use in a computer or related
computer hardware device.

3. Classification of Memory:

4. Primary Memory:

5. Primary Memory:
 This is the main memory of the computer.
 CPU can directly read or write on this
memory.
 It is fixed on the motherboard of the
computer.
 Primary memory is further divided in two
types:
1.RAM(Random Access Memory)
2.ROM(Read Only Memory)

6. RAM (Random Access Memory):
 RAM is a temporary memory.
 The information stored in this memory is lost as the
power supply to the computer is turned off.
 That’s why it is also called Volatile Memory. It stores
the data and instruction given by the user and also
the results produced by the computer temporarily.

7.  SRAM : (Static Random Access Memory)
 SRAM (static RAM) is random access memory (RAM) that retains
data bits in its memory as long as power is being supplied.
 SRAM does not have to be periodically refreshed.
 Static RAM provides faster access to data and is more expensive
than DRAM.
 SRAM is used for a computer's cache memory and as part of
the random access memory digital-to-analog converter on a video
card.
 DRAM : (Dynamic Random Access Memory)
 DRAM is a type of RAM that stores each bit of data on a separate
capacitor.Still, because DRAM can hold more data than SRAM.
 it is significantly less expensive to manufacture, DRAM is the
most common type of memory found in personal computer
systems.

8. ROM (Read Only Memory)
 Read-only memory (ROM) is a type of storage
medium that permanently stores data on personal
computers (PCs) and other electronic devices.
 It contains the programming needed to start a PC,
which is essential for boot-up; it performs major
input/output tasks and holds programs or software
instructions.
 ROM is non-volatile, which means it keeps its
contents regardless of whether or not it has power.

9. Types of ROM:

10.  MROM – (Mask Read Only Memory)
- it is the short form of Mask Read Only Memory. It is
inexpensive and is the very first ROM which is hard wired
device that contains a pre-programmed set of data or
instructions.
 PROM – (Programmable Read Only Memory)
- it is read-only memory chip that data can be written only once
by a user. The difference between it and the read only memory
is that PROM is manufactured as a blank memory, while the
ROM is programmed during the manufacturing process.
 EPROM – (Erasable Programmable Read Only Memory)
- it is a special kind of read only memory chip that has the
opportunity to erase the programmed data, which the feature
can be seen from its name. The programmable read-only
memory can be programmed to write data with high voltage,
and the data remains until it is exposed to ultraviolet light for
lasting up to 10 minutes or longer.

11.  EEPROM – (Electrically Erasable and Programmable Read
Only Memory)
- it is also a kind of read only memory that the principle of
operation is similar to EPROM which we have mentioned,
but the ways to program and erase are done by exposing it
to an electrical charge, so no transparent window is needed.
- It can be erased and reprogrammed about 10,000 times.
Both erasing and programming take about 4 to 10
milliseconds.
 Flash Memory
- Flash memory (flash) is a modern type of EEPROM. Flash
memory can be erased and rewritten faster than ordinary
EEPROM, and newer designs has the feature that is very
high endurance (exceeding 1,000,000 cycles).
-

12. Secondary Memory:
 It is also called external memory.
 Secondary memory refers to storage devices, such as
hard drives and solid state drives.
 That means the computer has roughly 64 times
more secondary memory than primary memory.
 Additionally, secondary memory is non-volatile,
meaning it retains its data with or without electrical
power.

14.  What is virtual memory?
- it is a memory management capability of an operating
system (OS) -- which uses hardware and software to
allow a computer to compensate for physical memory
shortages, by temporarily transferring data from random
access memory (RAM) to disk storage.

15. Computer memory measurement
units:

16. Sources:
 Wikipedia
Thank You
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