Memory is essential for computers and comes in primary and secondary forms. Primary memory, also called RAM, is volatile and directly used by the CPU. It includes DRAM and SRAM. Secondary memory is non-volatile storage like hard disks, SSDs, USB drives, and optical discs used for long-term storage. Common memory modules that plug into the motherboard include SIMMs, DIMMs, SO-DIMMs, and RIMMs which vary in size and pin count.

1. FATHIMA THENSILA .C
NO:- 13

2. Memory is the most essential part of a
computer.
Without memory there would be no
computer, as we know it today.
It is used for storing both instructions to be
executed and data.
The CPU accesses each location in
memory by using a unique number, called
a memory address

3. Central Processing Unit
Output
Devices
Cache
Memory
Primary
Storage
Secondary
Storage
Devices
Control
Unit
ALU
Special
Purpose
Processors
Output
Devices
Input
Devices

4. I. PRIMARY MEMORY OR MAIN MEMORY
Random Access Memory (RAM)
Read Only Memory (ROM)
II. CACHE MEMORY
 Level 1 (L1) cache
 Level 2 (L2) cache
III. SECONDARY MEMORY
Optical Media Devices
Magnetic Media Devices

5.  Directly or indirectly connected to the CPU via a memory
bus.
 Comprises of two buses: an address bus and a data bus
 The CPU firstly sends a number through an address bus,
a number called memory address, that indicates the
desired location of data. Then it reads or writes the data
itself using the data bus.
 Additionally, A Memory Management Unit (MMU) is a
small device between CPU and RAM recalculating the
actual memory address, for example to provide an
abstraction of virtual memory or other task.

6.  Broadly, the main memory is of two types-
i. Random Access Memory (RAM)
ii. Read Only Memory (ROM).

8. Memory is a collection of cells, each with a
unique physical/memory address
Each cell can hold one byte or 8 bits

10. A RAM memory chip is an integrated
circuit (IC) made of millions of transistors
and capacitors.
 RAM is volatile (temporary). Programs
and data can be written to and erased from
RAM as needed. This means that RAM
does not retain its bit configuration when
the power is turned off.

11.  This is a type of memory serves as Main
Memory Of A Computer.
 It temporarily stores copy of information and
files loaded from a computer hard drive that
are required by a processor.
 RAM stores data randomly and the processor
accesses these data randomly from the RAM
storage

13. There are two different types of RAM:
DRAM (Dynamic Random Access Memory)
SRAM (Static Random Access Memory).
The two types of RAM differ in the
technology they use to hold data, with
DRAM being the more common type.

14. Dynamic random-access memory (DRAM)
is a type of random-access memory that
stores each bit of data in a separate
capacitor within an integrated circuit.

15. DRAM chips are available in various
designs:
i. EDODRAM (Extended Data Out DRAM)
ii. SDRAM (Synchronous DRAM)
iii. RDRAM (Rambus DRAM)
iv. DDRDRAM (Double Data Rate DRAM)

16. SRAM is a type of memory that is faster
and more reliable than the more common
DRAM (dynamic RAM). The term static is
derived from the fact that it doesn't need to
be refreshed like dynamic RAM.

18. Different types of SRAM are:
Asynchronous SRAMs
Synchronous SRAMs
Special SRAMs
Non-Volatile RAM (NVRAM) and Battery-Back
SRAM (BRAM)

20. It performs only read function not write
function. So the data stored in ROM
cannot be modified.
ROM is non-volatile

21.  PROM: programmable ROM
Only written once
 EPROM: erasable PROM
Use ultraviolet light to erase data
 EEPROM: electronically EPROM
Can be erased using electronic impulses
(higher voltages)

22.  It is a high speed storage mechanism
 It Can be either a reserved section of
main memory or an independent storage
device.
 It speeds up access to data and
instructions stored in RAM.

23. MEMORY CACHE:-
It is a portion of memory of SRAM instead of the
slower DRAM. By keeping as much of the
information as possible in high speed SRAM, it
avoids accessing the slower DRAM.
 DISK CACHE:-
 It works under the same principle, but uses
conventional main memory (DRAM) instead of
high speed SRAM. It improves the computers
performance a lot as accessing data from RAM
is much faster than from hard-disk.

24.  Level 1 (L1) cache
 Built inside the CPU.
 It works at half CPU clock speed.
 Level 2 (L2) cache
 Built external to CPU, in the motherboard.
 It works at the motherboard bus speed
 Nowadays both L1 and L2 are integrated
in the CPU to reduce access time and
further improve system performance.

27.  Storage devices hold data, even when the
computer is turned off.
 The physical material that actually holds data is
called a storage medium. The surface of a floppy
disk is a storage medium.
 The hardware that writes data to or reads data
from a storage medium is called a storage
device. A floppy disk drive is a storage device.
 The two primary storage technologies are
magnetic and optical.

28.  Magnetic storage uses different patterns
of magnetization in a magnetizable
material to store data.
 It is a form of non-volatile memory.
 The information is accessed using one or
more read/write heads.
 HARD DISKS and FLOPPY DISKS are
such devices.

29. It stores information on one or more
continuously spinning disks which are
coated with magnetic material.

30. Information is recorded by magnetic heads
called access arms.
These days, hard disks have storage
capacity between 80 to 300 GB.

31.  It is made of a flexible substance called
Mylar.
 It has a magnetic surface for recording
data.
 It stores up to 1.44 MB of data.

32.  It cannot include
graphics or pictures
within it.
 All floppy disks must
be formatted before
data can be written
on it.

33. These are generally circular disc which
can contain data encoded in bumps on a
special material on one of its flat surfaces.
The encoding pattern follows a continuous,
spiral path covering the entire disc surface
and extending from the innermost track to
the outermost track.

34. The data is stored on the disc with
a laser or stamping machine, and can be
accessed when the data path is illuminated
with a laser diode in an optical disc drive
Optical storage devices are mainly two
types:
CD
DVD

35.  CDs are very cheap and
store up to 700MB
of data.
 They are of three
types:-
1. CD-ROM (CD Read Only Memory)
2. CD-R (CD Recordable)
3. CD-RW (CD Rewritable

36. It is of the same size as a CD but stores 15
times as much information, is 20 times
faster than it.
It can hold 17 GB of data.

37. It comes in three varieties:-
1.DVD-ROM (DVD Read Only Memory)
2.DVD-R (DVD Recordable)
3.DVD-RW (DVD Rewritable)

38. FLASH MEMORY
 Is a non-volatile memory
 It is a specific type of EEPROM
 Primarily used in memory cards and USB flash
drive

39. BLU-RAY DISK
Supersedes DVDs
Uses blue-violet laser to read the disc
stores almost six times more data than on a DVD

40. Different types of memory modules are:-
DIMM(DUAL IN-LINE MEMORY MODULE)
SO-DIMM(Small outline DIMM)
M-DIMM(MICRO DIMM)
SIMM(SINGLE IN-LINE MEMORY MODULE)
RIMM(RAMBUS IN-LINE MEMORY MODULE)

41.  SIMM stands for Single In-Line Memory
Module.
 A SIMM consist of memory chips soldered
onto a modular printed circuit board (PCB),
which inserts into a socket on the
motherboard.
 72 pin SIMMs transfer 32 bits of data at a
time, therefore in modern microcomputers
with a 64-bit data bus two SIMMs have to be
paired up in order to function.

42. • 30 pin SIMM - 1st gen. of SIMM (286,386 CPU
– 8 & 9 bit parity configuration)

43. Dual In-line Memory Modules, or DIMMs,
closely resemble SIMMs.
DIMMs install vertically into expansion
sockets.
 The difference between the two is that on
a SIMM, pins on opposite sides of the
board are "tied together" to form one
electrical contact; on a DIMM, opposing
pins remain electrically isolated to form two
separate contacts.

44. Single-sided DIMM
• Memory chips installed on one side of module
Double-sided DIMM
• Memory chips installed on both sides of module
Memory bank
• Memory processor addresses at one time.
• 64 bits wide
 DIMMs can always be installed as single DIMMs on a
motherboard

45. • 168 Pin DIMM
• 72 Pin SODIMM:- Used in p2 Laptop computer.
• 144 Pin SODIMM:- Found in Laptop.
• 100 Pin DIMM:- Used in Printers.
• 100 Pin RIMM
• 184 Pin DIMM:- Used on MotherBoards.
• 200 Pin SODIMM

46. 168-pin DIMMs transfer 64 bits of data at a
time and are typically used in computer
configurations that support a 64-bit or
wider memory bus.

47. A type of memory commonly used in
notebook computers is called SO DIMM or
Small Outline DIMM.
 The principal difference between a SO
DIMM and a DIMM is that the SO DIMM,
because it is intended for use in notebook
computers, is significantly smaller than the
standard DIMM.

48. The 72-pin SO DIMM is 32 bits wide and
the 144-pin SO DIMM is 64 bits wide.
72-Pin SO-DIMM 144-pin SO-DIMM

49.  These are 64-bit memories developed by
Rambus.
 RIMMs look similar to DIMMs, but have
a different pin count.
 RIMMs transfer data in 16-bit chunks.
 The faster access and transfer speed
generates more heat. An aluminum
sheath, called a heat spreader, covers the
module to protect the chips from
overheating.

50.  These are also called RD-RAM or DRD-
RAM.
 They have 184 pins.
 These modules have two locating notches
to avoid risk of confusion with the previous
modules.
 Smaller modules known as SO-RIMM
(Small Outline RIMM) have been designed
for portable computers.
 SO RIMM modules have only 160 pins.

51. Memory is the most essential part of a
computer.
Two types of Memory Primary Memory and
Secondary Memory.
And the different types of Memory modules
are
• Single In-line Memory Module
• Dual In-line Memory Module
• Rambus In-line Memory Module