Computer Memory and storage

Introduction

Computer memory and storage are essential components that enable a computer to process, store, and retrieve data efficiently. Memory is temporary and used for fast processing, while storage is permanent and used to save data for long-term use.

Types of Computer Memory

1. Primary Memory (Volatile Memory) 🖥️

Directly accessed by the CPU for fast data retrieval.
Temporary and loses data when power is off.
Examples: RAM (Random Access Memory) and Cache Memory.

a. RAM (Random Access Memory)

Stores data and instructions currently in use.

The more RAM a system has, the better its performance.

Types:

SRAM (Static RAM) – Faster but expensive, used in cache memory.
DRAM (Dynamic RAM) – Slower but cheaper, used in main memory.

b. Cache Memory

High-speed memory between CPU and RAM.
Stores frequently accessed data to speed up processing.

c. Registers

Small, high-speed storage areas within the CPU.
Store instructions and data during execution.

d. ROM (Read-Only Memory) (Non-Volatile Memory)

Stores firmware (essential programs like BIOS).

Retains data even when the computer is powered off.

Types:

PROM (Programmable ROM) – Can be programmed once.
EPROM (Erasable Programmable ROM) – Can be erased and reprogrammed.
EEPROM (Electrically Erasable Programmable ROM) – Can be reprogrammed multiple times electronically.

2. Secondary Storage (Non-Volatile Storage) 💾

Stores data permanently for long-term use.

Slower than primary memory but provides high storage capacity.

Examples: HDD, SSD, Flash Drives, Optical Discs.

a. Hard Disk Drive (HDD)

Traditional storage device with spinning magnetic disks.
Large storage capacity (500GB to 10TB).
Slower than SSDs but cost-effective.

b. Solid-State Drive (SSD)

Uses flash memory for faster data access.
No moving parts, making it durable and energy-efficient.
Common in modern laptops and high-performance PCs.

c. Flash Memory (USB Drives, SD Cards)

Portable and used for quick data transfer.
USB Flash Drives (Pen Drives) and Memory Cards (SD, MicroSD).

d. Optical Storage (CD, DVD, Blu-ray)

Stores media and software.
CD (Compact Disc): 700MB capacity.
DVD (Digital Versatile Disc): 4.7GB to 17GB.
Blu-ray Disc: Up to 128GB, used for high-definition videos.

3. Tertiary Storage (Backup Storage) 🔄

Used for long-term archiving and backups.
Examples: Magnetic Tape Drives, Cloud Storage.
a. Magnetic Tape
Used for massive data storage (corporate backups).
Slower access speed but highly durable.
b. Cloud Storage ☁️
Data stored on remote servers via the internet.
Examples: Google Drive, OneDrive, Dropbox.

Memory Hierarchy Table

Level	Memory Type	Speed 🔥	Cost 💰	Capacity 📦	Volatile	Function
L1	CPU Registers	Fastest	Very High	Very Small (Bytes)	Yes	Stores instructions & data for immediate execution.
L2	Cache Memory (L1, L2, L3)	Very Fast	High	Small (KB to MB)	Yes	Stores frequently accessed data for quick retrieval.
L3	Primary Memory (RAM)	Fast	Medium	Moderate (GBs)	Yes	Temporary storage for active programs & OS.
L4	Secondary Storage (SSD/HDD)	Slow	Low	Large (GBs to TBs)	No	Stores OS, applications, files, and documents permanently.
L5	Tertiary Storage (Magnetic Tape, Cloud Storage)	Slowest	Very Low	Massive (TBs to PBs)	No	Used for data backup, archival, and cloud storage.

Memory Units in Computers

Memory units measure the amount of data a computer can store and process. The smallest unit of memory is a bit, while larger units are measured in bytes, kilobytes, megabytes, and beyond.

Memory Units Table

Unit	Symbol	Size (Bytes)	Equivalent
Bit	b	Smallest unit	0 or 1 (Binary Digit)
Nibble	-	4 Bits	Half a Byte
Byte	B	8 Bits	1 Character (e.g., ‘A’ or ‘9’)
Kilobyte	KB	1,024 Bytes	Small text file (~1 page)
Megabyte	MB	1,024 KB	A short MP3 song (~4MB)
Gigabyte	GB	1,024 MB	A full HD movie (~4-8GB)
Terabyte	TB	1,024 GB	A large external hard drive
Petabyte	PB	1,024 TB	Large-scale cloud storage
Exabyte	EB	1,024 PB	Massive global data storage
Zettabyte	ZB	1,024 EB	Internet-scale data
Yottabyte	YB	1,024 ZB	Beyond current technology

Qus. 1 : The access method used for magnetic tape is

Direct
Random
Sequential
Indexed

Qus. 2 : The instructions or programs that are loaded into main memory when a computer is booted are

Internal commands.
External commands.
Utility Programs.
Bootloader

Qus. 3 : The factor that does not affect the storage capacity of a hard disk

Track density
Height of the hard disk drive
Recording density
Number of plates

Qus. 4 : Main function of shared memory is:

to use primary memory efficently
to do intra process communication
to do inter process communication
None of above

Qus. 5 : EEPROM stands for

Electrically Erasable Programmable Read Of Memory
Erasable Electrically Programmable Read Only Memory
Easily Erasable Programmable Read Only Memory
Electrically Erasable Programmable Read Only Memory

Qus. 6 : An example of a volatile memory is:

CD-ROM
RAM
ROM
Hard Disk

Qus. 7 : Which of the following is a storage device?

Tape
Hard Disk
Floppy Disk
All of the above

Qus. 8 : 1024 bits equal to

1KB
1MB
128 bytes
None of The Above

Qus. 9 : This is a volatile type of memory used only for temporary storage while a program is running.

RAM (Random Access Memory)
Secondary Storage
The disk drive
The USB drive

Qus. 10 : Which of the following component is the main memory of computer?

CD
DVD
Internal Hard Drive
RAM

Qus. 11 : What is the name of the component that used to both read and writes data

ROM
RAM
Hard Drive
Cache Memory

Qus. 12 : Flash memory and Blu Ray disk are the example of

Hardware
Software
CPU
None of these

Qus. 13 : Flash memory is a type of________memory

Primary
RAM
Secondary
All of these

Qus. 14 : Which of the following memory types will store the data or information permanently

RAM
Cache
Register
Hard disk

Qus. 15 : Which of the following memory types cannot store the data or information permanently ?

RAM
ROM
Flash Memory
Hard disk

Qus. 16 : What Is The Capacity of A 3.5 Inch Floppy Disk?

1.40 Mb
1.44 Gb
1.40 Gb
1.44 Mb

Qus. 17 : Which of the following memory devices is very much similar, mailny in terms of speed, to the cache memory?

Flash Memory
DRAM
SRAM
EEPROM

Qus. 18 : Which among the following memories is used in Digital Camera?

Virtual Memory
Flash Memory
Main Memory
Cache Memory

Qus. 19 : Information in computer on read only memory is stored by :

User
Programmer
Manufacturer
Engineer

Qus. 20 : 1 kilobyte is equals to :

1024 bytes
1048576 bytes
102400 bytes
1048 bytes

Qus. 21 : Which of the following options shows the correct storage device hierarchy in terms of decreasing access time?

magnetic tape, magnetic disk, cache, main memory
magnetic disk, optical disk, main memory, register
magnetic tape, magnetic disk, main memory, register
register, main memory, magnetic disk, magnetic tape

Qus. 22 : 1 Petabytes (PB) of memory is equal to how many Gigabytes (GB) ?

1024 GB
1048576 GB
524288 GB
4194304 GB

Qus. 23 : What is full form of ODMR?

On-Demand Mail Relay
Online Demand Mail Relay
Online Delivery Mail Relay
On-Demand Mail Reply

Qus. 24 : What is the Full Form of SSD

Soft State Drive
Solid State Disk
Solid State Drive
Soft State Disk

Qus. 25 : The saving of data and instruction to make them available for later use is a job of

Cache unit
Input unit
Output unit
Storage unit

Qus. 26 : What is the primary purpose of an SSD (Solid State Drive)?

To provide power to the computer
To store data
To connect to a network
To increase processing speed

Qus. 27 : What is the purpose of a solid-state drive (SSD) in modern laptops and desktops

To improve the graphical rendering capabilities of the system.
To provide high-speed data storage and faster read/write performance.
To enhance network connectivity and internet speed.
To act as a backup power source during outages.

Qus. 28 : Which of the following devices uses optical technology for data storage

Hard Disk Drive (HDD)
Solid-State Drive (SSD)
CD-ROM
RAM

Qus. 29 : What is the role of virtual memory in a computer system

Increase the clock speed of the CPU
Simulate additional RAM using storage space
Store frequently used data for quick access
Boost graphical performance

Qus. 30 : What is the function of the registers in a CPU

Store frequently used data and instructions for quick access
Perform arithmetic operations
Manage power supply to the CPU
Control input/output devices

Qus. 31 : What type of storage is a Solid State Drive (SSD)

Optical storage
Magnetic storage
Volatile storage
Flash memory

Qus. 32 : The main memory of a computer is also called

ROM
RAM
Cache memory
Hard disk

Qus. 33 : What is the smallest unit of data in a computer system

Byte
Bit
Nibble
Word

Qus. 34 : Virtual memory is part of

RAM
Hard disk
ROM
Cache

Qus. 35 : Match the following terms with their correct descriptions.<table class="table table-bordered"><tbody><tr><td>Terms</td><td>Descriptions</td></tr><tr><td>A. CPU</td><td>1. Non-volatile storage device</td></tr><tr><td>B. RAM</td><td>2. Executes program instructions</td></tr><tr><td>C. Hard Disk Drive</td><td>3. Temporary storage for active processes</td></tr><tr><td>D. Operating System</td><td>4. Interface between hardware and software</td></tr></tbody></table>

A-2, B-3, C-1, D-4
A-3, B-4, C-2, D-1
A-1, B-2, C-4, D-3
A-4, B-1, C-3, D-2

Qus. 36 : Match the following types of memory with their characteristics.<table class="table table-bordered"><tbody><tr><td>Memory Type</td><td>Characteristics</td></tr><tr><td>A. RAM</td><td>1. Non-volatile memory</td></tr><tr><td>B. ROM</td><td>2. High-speed memory close to CPU</td></tr><tr><td>C. Cache Memory</td><td>3. Simulated memory using storage</td></tr><tr><td>D. Virtual Memory</td><td>4. Volatile memory</td></tr></tbody></table>

A-1, B-2, C-3, D-4
A-2, B-3, C-4, D-1
A-4, B-1, C-2, D-3
A-3, B-4, C-1, D-2

Qus. 37 : Arrange the following memory types in the correct order from lowest to highest in speed and cost:1️⃣ Hard Disk Drive (HDD)2️⃣ Cache Memory3️⃣ Registers4️⃣ RAM (Random Access Memory)5️⃣ Solid-State Drive (SSD)

1 → 4 → 5 → 2 → 3
4 → 2 → 3 → 5 → 1
3 → 2 → 4 → 5 → 1
1 → 5 → 4 → 2 → 3

Qus. 38 : Arrange the following storage devices based on access speed from slowest to fastest:1️⃣ HDD (Hard Disk Drive)2️⃣ RAM (Random Access Memory)3️⃣ SSD (Solid State Drive)4️⃣ Cache Memory

1 → 3 → 2 → 4
3 → 2 → 1 → 4
1 → 2 → 3 → 4
4 → 3 → 2 → 1

Introduction

Types of Computer Memory

Memory Hierarchy Table

Memory Units in Computers

Programs