MEMORY AND

STORAGE SYSTEM
RINABETH MEGIO

CYRIL CARAMPATAN
What is Memory?

Memory is the storage space in computer where data is

to be processed and instructions required for processing
are stored.
The memory is divided into large number of small parts
called cells. Each location or cell has a unique address which
varies from zero to memory size minus one.
 The Kinds of memory

1. RAM (Random Access Memory).

2. ROM (Read Only Memory).
3. Cash Memory.
1. Random Access
Memory (RAM)
is the main memory in a computer, where data and
programs that are currently being processed are
actively stored for quick access by the processor.
Random
Access
It is a volatile type of memory, meaning its Memory
(RAM)
contents are lost when the computer is powered
off.
2. Read only Memory (ROM)

is a type of non-volatile memory that

stores essential data permanently.
the data in ROM is not lost when the Read on
ly
Memory
(ROM)
computer is powered off.
3. Cache Memory
is a small, high-speed memory
located close to or inside the CPU. It
temporarily stores frequently used
data and instructions to speed up
processing. Cache M
emory
What is Storage System?

refers to the hardware and software

used to store, manage, and retrieve
data in a computer or network. It
ensures that data remains available
even after the computer is turned off.
 Type of Storage System
1. Primary Storage (Volatile Memory) – Fast but Temporary.

• RAM (Random Access Memory) – Stores active programs and

data temporarily. Data is lost when power is off.
• Cache Memory – Super-fast memory inside the CPU for frequently
2. Secondary Storage (Non-Volatile) – Permanent Storage
accessed data.

• HDD (Hard Disk Drive) – Uses spinning disks to store data. Large capacity but slower
than SSDs.
• SSD (Solid-State Drive) – Uses flash memory for faster data access and boot times.
• Hybrid Drives (SSHD) – A mix of HDD and SSD for balanced performance and
storage capacity.
Type of Storage System
3. External Storage – Portable and Backup Options.
• USB Flash Drive – Small, portable, and uses flash memory.
• External HDD/SSD – Used for backup or extra storage.
• Memory Card (SD Card) – Commonly used in cameras, smartphones, and
laptops.

4. Cloud Storage – Online Data Storage.

• Google Drive, OneDrive, Dropbox – Store files on remote servers and access them
via the internet.
• Cloud Backup (AWS, iCloud, etc.) – Used by businesses for secure and scalable
data storage.
 Type of Storage System
5. Network Storage – Shared Storage for Multiple Devices.

• NAS (Network Attached Storage) – A personal or business storage device

connected to a network.
• SAN (Storage Area Network) – High-speed storage used by enterprises for
managing large data.
SSDS VS.
HDDS:
PERFORMANCE Solid State
Drive

VS
(SSD)
COMPARISON
UNDERSTANDING THE DIFFERENCES
i v e
AND THEIR IMPACT ON SYSTEM D r
PERFORMANCE. i s k
d D )
r D
Ha (H
D

Grefalde Troy
Venerable Jorge Louise
 THERE ARE CURRENTLY TWO PRIMARY TYPES OF
STORAGE USED TODAY ARE HARD DISK DRIVES (HDDS) AND
SOLID-STATE DRIVES (SSDS)

SOLID STATE DRIVE HARD DISK DRIVE

(SSD) (HDD)

GO TO NEXT PAGE
 SSD
WHAT IS AN SSD?
A Solid-State Drive (SSD) is a storage device that uses flash memory
chips instead of moving parts. It stores data electronically, allowing
much faster access to files and programs. Because SSDs do not rely on
spinning disks, they are more durable, energy-efficient, and silent
compared to HDDs.
 HDD
WHAT IS AN HDD?
A Hard Disk Drive (HDD) is a device used for storing and retrieving
digital data using magnetic storage on rotating disks called platters. It
records and accesses data through a mechanical arm with a
read/write head that moves across the spinning platters. HDDs are
commonly used in computers, servers, and external storage devices to
store operating systems, software, and files.
PERFORMANCE
COMPARISON
FEATURES SSD HDD
Much faster, with Slower, with
SPEED
read/write speeds read/write speeds

Boots an OS in seconds Boots an OS in

BOOT TIME
(5–15 sec). (30 seconds or more).

Transfers large files faster due Transfers large files slower due
DATA TRANSFER
to no mechanical parts. to spinning disks.

Applications and games load Applications and games take

LOAD TIMES
instantly or much quicker. longer to load.
PERFORMANCE
COMPARISON
FEATURES SSD HDD
More prone to damage from
More resistant to physical
DURABILITY drops or shocks due to
shocks due to no moving parts.
mechanical parts.

Consumes less power (better Consumes more power due to

POWER USAGE
for laptops and battery life). spinning disks.

Longer lifespan, especially Shorter lifespan, mechanical

LIFESPAN
with wear-leveling technology. parts wear out over time.
CACHE
ORGANIZATION
AND MAPPING
TECHNIQUES
Mark Lester J. Real
Reynard Mata
ESSENTIAL FOR IMPROVING THE
EFFICIENCY OF MEMORY ACCESS IN
COMPUTER ARCHITECTURE
CACHE ORGANIZATION
• refers to the structure and working mechanism of a cache
memory system in a computer.

• It determines how data is stored, accessed, and managed for

efficient memory performance.
WHY IS IT IMPORTANT?
• Performance Improvement
• Locality of Reference
• Cache Hierarchy
CACHE MEMORY
• is a small, high-speed
memory located close to the
processor to reduce access
time to frequently used data
from main memory (RAM).
Cache Hit ✅ Cache Miss❌
REPLACING OLD DATA
• Since cache is small, when new data comes in and there’s no
space, old data must be removed.

Replacement Policies:
• Least Recently Used (LRU): Remove the data that hasn’t been
used for the longest time.

• First-In-First-Out (FIFO): Remove the oldest stored data.

• Random Replacement: Remove any random data.

KEY ASPECTS OF CACHE ORGANIZATION
• Cache Size: The total amount of memory allocated to the cache,
which directly impacts the amount of data that can be stored.

• Block Size: Each main memory block can be stored in any of a set of
cache lines.

• Associativity: How many cache lines can store data from a given
main memory block.
⚬ Direct Mapping
⚬ Fully Associative Mapping
CACHE MAPPING
is how the computer decides where to store data from main memory
in the cache. It follows a specific pattern to transfer data and find its
location in the cache. Memory is divided into small blocks, and each
block is assigned a specific place in the cache for quick access.
TYPES OF CACHE MAPPING TECHNIQUES
1. Direct Mapping
• Each data has a fixed spot
The physical address is divided into:
• Tag bits – Identify the main memory block in the cache.
• Cache Line Number – Specifies the cache line storing the block.
• Byte Offset – Locates the exact byte within the block.
TYPES OF CACHE MAPPING TECHNIQUES
Direct Mapping diagram
TYPES OF CACHE MAPPING TECHNIQUES
2. Fully Associative Mapping
• Data will be place anywhere
In Fully Associative Mapping the physical address is divided into:
• Tag bits – Identify which memory block is in the cache.
• Byte Offset – Determine the exact byte within the block.
TYPES OF CACHE MAPPING TECHNIQUES
Fully Associative
Mapping
diagram
TYPES OF CACHE MAPPING TECHNIQUES
2. Set Associative Mapping
• Organizing Data into Sections
In set-associative mapping, the physical address is divided into:
• Tag bits – Identify which memory block is in the cache.
• Set Number – Determine the cache set where the block is placed.
• Byte Offset – Specify the exact byte within the block.
TYPES OF CACHE MAPPING TECHNIQUES
Set Associative
Mapping
MEMORY
MANAGEMENT
IN OPERATING
SYSTEMS
MEMORY MANAGEMENT IS A KEY FUNCTION OF
AN OPERATING SYSTEM (OS) THAT HELPS A
COMPUTER MANAGE HOW PROGRAMS USE
MEMORY (RAM). IT ENSURES THAT DIFFERENT
APPLICATIONS GET ENOUGH MEMORY TO RUN
WITHOUT INTERFERING WITH EACH OTHER.
WHAT IS MEMORY MANAGEMENT?
• A function of the OS that manages RAM.

• Allocates memory to programs and ensures efficient use.

• Prevents programs from interfering with each other.

MEMORY ALLOCATION METHODS
1. Contiguous Allocation
• Assigns a single continuous block of memory to a process.
• Simple but can lead to fragmentation (wasted space).
2. Paging
• Splits memory into fixed-size blocks called pages.
• Pages can be placed anywhere in RAM, reducing fragmentation.
• Uses a page table to keep track of where pages are stored.
3. Segmentation
• Divides programs into logical segments (e.g., functions, arrays).
• Segments can be different sizes, making it more flexible than paging.
VIRTUAL MEMORY – EXPANDING RAM
• Virtual memory extends RAM by using hard disk space as temporary
memory.

• Allows more programs to run than physical RAM can hold.

• Uses swapping, where inactive programs are temporarily moved to the

disk.

• Slower than actual RAM but necessary for multitasking.

 MANAGING MEMORY EFFICIENTLY
1.Swapping
• When RAM is full, the OS moves some processes to the swap space on the hard drive.
• When needed, they are swapped back into RAM.

2. Page Replacement Algorithms (When RAM is full, the OS must replace some data)
• FIFO (First-In-First-Out): Removes the oldest page in memory.
• LRU (Least Recently Used): Removes the page that hasn’t been used for the longest time.
• Optimal Algorithm: Removes the page that will not be used for the longest time (ideal but
hard to predict).
MEMORY PROTECTION & SECURITY

• Memory Boundaries: Ensures one program cannot access another program’s memory.

• Permission Levels: Memory can be set as read-only, executable, or restricted.

• Hardware Support (MMU - Memory Management Unit): Translates virtual addresses to

physical memory and prevents unauthorized access.
 MEMORY FRAGMENTATION

1. External Fragmentation
• Free memory is available but scattered, making it hard to allocate large blocks.

2. Internal Fragmentation
• A process gets more memory than it actually needs, wasting space.
• Solution – Compaction
• The OS rearranges memory to create larger free blocks.
• Helps reduce wasted space and improve memory efficiency.
MULTI-CORE SYSTEMS & NUMA

• NUMA (Non-Uniform Memory Access): In multi-core processors, each processor accesses

its own local memory faster than shared memory.

• Improves speed and efficiency in high-performance computing.

• Reduces bottlenecks caused by multiple processors accessing the same memory.

RAM VS ROM
 What is
RAM?
RAM IS A VOLATILE, HIGH-SPEED MEMORY THAT TEMPORARILY STORES DATA AND
INSTRUCTIONS FOR ACTIVELY RUNNING PROGRAMS AND PROCESSES. IT ALLOWS THE CPU TO
QUICKLY ACCESS AND MODIFY DATA, IMPROVING SYSTEM PERFORMANCE AND MULTITASKING.
HOWEVER, DATA IS LOST WHEN POWER IS TURNED OFF.
How does RAM
work?
 How does RAM
work?
• CPU Requests Data – RAM loads data from storage for quick access.

• Data Stored in Memory Cells – Each cell has a unique address.

• Read/Write Operations – Data transfers via buses.

• Refreshing (For DRAM) – Prevents data loss in capacitors.

• Data Loss on Power Off – RAM is volatile; unsaved data is lost.

 What is
ROM?
ROM is a non-volatile memory that permanently stores essential data, such as firmware and
BIOS, required for system booting and hardware operation. Unlike RAM, it retains data even
without power and is mostly read-only, though some types (EEPROM, Flash) can be modified.
How does ROM
work?
 How does ROM
work?
• Pre-Programmed Data – ROM stores firmware and essential instructions.

• Non-Volatile Storage – Retains data even when power is off.

• Read-Only Access – Data is usually fixed, except in reprogrammable types.

• Used in Boot Process – Stores BIOS, operating system loader, and device firmware
 RAM vs

RAM
ROM ROM

Temporary, high-speed memory for active processes. Permanent memory for firmware and system data.

Volatile – data is lost when power is off. Non-volatile – retains data permanently.

Faster (nanoseconds). Slower (microseconds).

Read & write. Mostly read-only (some reprogrammable types).

Larger (GBs to TBs). Smaller (MBs to a few GBs).

System memory, caching, multitasking. BIOS, firmware, embedded systems.