HARDWARE AND OPERATION | SECONDARY STORAGE
DESIGNED FOR IB EXAMINATIONS
OBJECTIVES
A1.1.7 Describe internal and external types of secondary memory storage.
A1.1.7 Describe internal and external types of secondary memory storage.
- Internal hard drives: solid state drive (SSD), hard disk drive (HDD), embedded multimedia cards (eMMCs)
- External hard drives: SSD, HDD, optical drives, flash drives, memory cards, network attached storage (NAS)
- The scenarios in which the various types of drive are use
Unlike primary storage, which provides fast access to frequently used data, secondary storage devices typically have slower access speeds but offer much larger storage capacity. This makes them ideal for storing large files such as videos, photos, and documents, as well as backups of important data.
Examples of secondary storage devices include:
Secondary storage is an essential component of modern computing, providing a reliable and cost-effective way to store large amounts of data for long periods of time.
Persistent storage is needed to store data in a non-volatile device during and after the running of a program because it provides a way to store data that needs to be preserved even when the power is turned off or the program is no longer running.
During the running of a program, data is typically stored in primary storage, such as RAM. While this provides fast access to frequently used data, it is volatile and the data is lost when the computer is turned off or the program is terminated. This means that any data that needs to be preserved must be stored in persistent storage.
After the running of a program, persistent storage is necessary to store any data that needs to be saved for future use. This includes files, documents, and other data that the program creates or modifies. By storing this data in non-volatile devices, such as hard disk drives, solid-state drives, or other secondary storage devices, the data is preserved even after the program has ended.
Persistent storage is also important for system backups and disaster recovery. By storing backups of important data in non-volatile devices, businesses and individuals can ensure that they can recover their data even in the event of a system failure or other catastrophic event.
Persistent storage is an essential component of modern computing, providing a reliable way to store and preserve data for long periods of time, even in the event of power loss or system failure
Examples of secondary storage devices include:
- Hard disk drives (HDD)
- Solid-state drives (SSD)
- Optical discs (CD, DVD, Blu-ray)
- USB flash drives
- Memory cards (SD, microSD)
- Magnetic tapes
- External hard drives
- Network-attached storage (NAS) devices
- Cloud storage services.
Secondary storage is an essential component of modern computing, providing a reliable and cost-effective way to store large amounts of data for long periods of time.
Persistent storage is needed to store data in a non-volatile device during and after the running of a program because it provides a way to store data that needs to be preserved even when the power is turned off or the program is no longer running.
During the running of a program, data is typically stored in primary storage, such as RAM. While this provides fast access to frequently used data, it is volatile and the data is lost when the computer is turned off or the program is terminated. This means that any data that needs to be preserved must be stored in persistent storage.
After the running of a program, persistent storage is necessary to store any data that needs to be saved for future use. This includes files, documents, and other data that the program creates or modifies. By storing this data in non-volatile devices, such as hard disk drives, solid-state drives, or other secondary storage devices, the data is preserved even after the program has ended.
Persistent storage is also important for system backups and disaster recovery. By storing backups of important data in non-volatile devices, businesses and individuals can ensure that they can recover their data even in the event of a system failure or other catastrophic event.
Persistent storage is an essential component of modern computing, providing a reliable way to store and preserve data for long periods of time, even in the event of power loss or system failure
SECTION 1 | INTERNAL HARD DRIVES
Secondary memory storage is used to store data and programs permanently, even when power is removed. Internal secondary storage devices are located inside the computer system and provide the main long-term storage for the operating system, applications, and user files.
Solid State Drive (SSD)
A solid state drive (SSD) stores data using non-volatile flash memory.
SSDs are commonly used as the primary internal storage device in modern desktops and laptops due to their speed and reliability. They significantly reduce boot times and application loading times.
Hard Disk Drive (HDD)
A hard disk drive (HDD) stores data on rotating magnetic disks known as platters.
HDDs are often used in systems where large amounts of storage are required, such as desktop computers, servers, or systems storing large media files, where speed is less critical than capacity.
Embedded Multimedia Card (eMMC)
An embedded multimedia card (eMMC) is a type of flash-based storage that is permanently attached to the system’s motherboard.
eMMCs are commonly used in low-cost laptops, tablets, and embedded systems where low power consumption and small size are priorities.
Comparison of Internal Storage Types
Summary
Internal secondary storage devices such as SSDs, HDDs, and eMMCs serve different purposes depending on performance requirements, cost constraints, and device design.
Solid State Drive (SSD)
A solid state drive (SSD) stores data using non-volatile flash memory.
- SSDs have no moving parts, unlike mechanical drives.
- Data is accessed electronically, resulting in very fast read and write speeds.
- SSDs are more resistant to physical shock and generate less heat and noise.
SSDs are commonly used as the primary internal storage device in modern desktops and laptops due to their speed and reliability. They significantly reduce boot times and application loading times.
Hard Disk Drive (HDD)
A hard disk drive (HDD) stores data on rotating magnetic disks known as platters.
- Data is read and written using a mechanical read/write head.
- HDDs have moving parts, which makes them slower than SSDs.
- They typically offer large storage capacities at a lower cost per gigabyte.
HDDs are often used in systems where large amounts of storage are required, such as desktop computers, servers, or systems storing large media files, where speed is less critical than capacity.
Embedded Multimedia Card (eMMC)
An embedded multimedia card (eMMC) is a type of flash-based storage that is permanently attached to the system’s motherboard.
- eMMCs are non-removable and integrated into the device.
- They are slower than SSDs but faster than many traditional removable storage devices.
- eMMCs are compact, energy-efficient, and inexpensive.
eMMCs are commonly used in low-cost laptops, tablets, and embedded systems where low power consumption and small size are priorities.
Comparison of Internal Storage Types
- SSD: Fast, durable, and energy-efficient; higher cost per gigabyte.
- HDD: Slower, mechanical, but offers high capacity at lower cost.
- eMMC: Integrated, low-cost flash storage suitable for lightweight devices.
Summary
- Internal secondary storage provides permanent data storage inside a computer system.
- SSDs prioritise speed and reliability.
- HDDs prioritise capacity and cost-effectiveness.
- eMMCs provide compact, low-power storage for embedded and low-cost systems.
Internal secondary storage devices such as SSDs, HDDs, and eMMCs serve different purposes depending on performance requirements, cost constraints, and device design.
Quick Check: Internal Secondary Storage
Which statement correctly compares internal SSDs, HDDs, and eMMCs?
A. HDDs are faster than SSDs because they use rotating magnetic platters.
B. SSDs provide fast access with no moving parts, HDDs offer large capacity at lower cost, and eMMCs are integrated flash storage used in low-power devices.
C. eMMCs provide the highest storage capacity and are mainly used in desktop computers.
D. SSDs and eMMCs both rely on mechanical components to store data.
SECTION 2 | EXTERNAL STORAGE
External secondary storage devices are storage media that are not permanently installed inside a computer system. They are typically connected using external interfaces such as USB, Thunderbolt, or a network connection. These devices are used for data transfer, backup, sharing, and long-term storage.
External Solid State Drives (SSD)
An external SSD uses flash memory to store data and connects to a computer through a high-speed interface.
External SSDs are commonly used for fast backups, transferring large files, and running applications or operating systems externally.
External Hard Disk Drives (HDD)
An external HDD stores data on rotating magnetic disks inside a protective casing.
External HDDs are often used for bulk storage, long-term backups, and archiving large media collections.
Optical Drives
Optical drives read and write data using laser technology.
Optical drives are used for software distribution, media playback, and long-term archival storage where data does not need to be modified frequently.
Flash Drives
A flash drive is a small, portable storage device that uses flash memory.
Flash drives are commonly used for transferring files between computers and for temporary storage.
Memory Cards
Memory cards are compact flash-based storage devices.
Memory cards are suitable for storing photos, videos, and data in portable electronic devices.
Network Attached Storage (NAS)
Network attached storage (NAS) is a storage system connected to a network rather than directly to a single computer.
NAS systems are commonly used in homes, schools, and businesses for shared storage and centralised data management.
Summary
External secondary storage devices serve a wide range of purposes, from personal data transfer to large-scale shared storage, depending on capacity, speed, portability, and access requirements.
External Solid State Drives (SSD)
An external SSD uses flash memory to store data and connects to a computer through a high-speed interface.
- No moving parts, making them durable and shock-resistant.
- Faster read and write speeds than most other external storage devices.
- Compact and portable.
External SSDs are commonly used for fast backups, transferring large files, and running applications or operating systems externally.
External Hard Disk Drives (HDD)
An external HDD stores data on rotating magnetic disks inside a protective casing.
- Larger storage capacities at a lower cost compared to SSDs.
- Slower than external SSDs due to mechanical components.
- Typically larger and heavier.
External HDDs are often used for bulk storage, long-term backups, and archiving large media collections.
Optical Drives
Optical drives read and write data using laser technology.
- Common formats include CD, DVD, and Blu-ray.
- Data is stored on removable optical discs.
- Slower access speeds compared to modern solid-state storage.
Optical drives are used for software distribution, media playback, and long-term archival storage where data does not need to be modified frequently.
Flash Drives
A flash drive is a small, portable storage device that uses flash memory.
- Connects via USB.
- Easy to carry and use.
- Limited storage capacity compared to external HDDs and SSDs.
Flash drives are commonly used for transferring files between computers and for temporary storage.
Memory Cards
Memory cards are compact flash-based storage devices.
- Common formats include SD and microSD cards.
- Widely used in cameras, smartphones, and embedded systems.
- Require a card reader or compatible slot to access data.
Memory cards are suitable for storing photos, videos, and data in portable electronic devices.
Network Attached Storage (NAS)
Network attached storage (NAS) is a storage system connected to a network rather than directly to a single computer.
- Accessible by multiple users and devices over a network.
- Often includes multiple drives for large capacity and redundancy.
- Can provide automated backup and file-sharing services.
NAS systems are commonly used in homes, schools, and businesses for shared storage and centralised data management.
Summary
- External storage devices provide flexibility, portability, and shared access.
- External SSDs and HDDs are used for fast access and large storage.
- Optical drives are suited to distribution and archival purposes.
- Flash drives and memory cards support portable data transfer.
- NAS provides centralised, network-based storage for multiple users.
External secondary storage devices serve a wide range of purposes, from personal data transfer to large-scale shared storage, depending on capacity, speed, portability, and access requirements.
Quick Check: External Secondary Storage
Which external storage device is most suitable for providing shared access to files for multiple users over a network?
A. USB flash drive
B. External hard disk drive (HDD)
C. Optical drive
D. Network attached storage (NAS)
SECTION 3 | STORAGE USAGE
Different types of secondary storage devices are designed to meet different needs. The choice of storage depends on factors such as speed, capacity, portability, cost, reliability, and access requirements. Understanding typical usage scenarios helps explain why multiple storage technologies coexist.
Solid State Drives (SSD)
Typical scenarios:
Reason for use:
SSDs are chosen when high performance and fast data access are required. Their lack of moving parts makes them reliable and suitable for both internal and external use, especially in laptops and modern desktops.
Hard Disk Drives (HDD)
Typical scenarios:
Reason for use:
HDDs are preferred when large storage capacity at low cost is more important than speed. They are well suited to storing data that is accessed infrequently.
Embedded Multimedia Cards (eMMC)
Typical scenarios:
Reason for use:
eMMCs are used where low power consumption, compact size, and low cost are priorities, even though performance is lower than SSDs.
Flash Drives
Typical scenarios:
Reason for use:
Flash drives are ideal for convenience and portability, allowing quick and simple data transfer without the need for additional hardware.
Memory Cards
Typical scenarios:
Reason for use:
Memory cards are designed for small, portable devices where removable storage is required and space is limited.
Optical Drives
Typical scenarios:
Reason for use:
Optical media is suitable for read-only or infrequently modified data, particularly when physical distribution or long-term preservation is required.
Network Attached Storage (NAS)
Typical scenarios:
Reason for use:
NAS devices are used when multiple users or devices need shared access to data over a network, providing centralised storage and management.
Summary
Different storage technologies are used in different scenarios to balance performance, capacity, cost, portability, and access needs. Understanding these scenarios explains why modern systems often use multiple types of secondary storage simultaneously.
Solid State Drives (SSD)
Typical scenarios:
- Boot drives for operating systems
- Running applications that require fast access
- Video editing, software development, and gaming
- Portable high-speed external storage
Reason for use:
SSDs are chosen when high performance and fast data access are required. Their lack of moving parts makes them reliable and suitable for both internal and external use, especially in laptops and modern desktops.
Hard Disk Drives (HDD)
Typical scenarios:
- Mass storage for large files such as videos and backups
- Desktop computers and servers requiring high capacity
- External backup drives for home or office use
Reason for use:
HDDs are preferred when large storage capacity at low cost is more important than speed. They are well suited to storing data that is accessed infrequently.
Embedded Multimedia Cards (eMMC)
Typical scenarios:
- Low-cost laptops and tablets
- Embedded systems such as smart devices
- Devices with limited power and space
Reason for use:
eMMCs are used where low power consumption, compact size, and low cost are priorities, even though performance is lower than SSDs.
Flash Drives
Typical scenarios:
- Transferring files between computers
- Temporary storage of documents and presentations
- Personal portable storage
Reason for use:
Flash drives are ideal for convenience and portability, allowing quick and simple data transfer without the need for additional hardware.
Memory Cards
Typical scenarios:
- Digital cameras and video cameras
- Smartphones, tablets, and drones
- Embedded and IoT devices
Reason for use:
Memory cards are designed for small, portable devices where removable storage is required and space is limited.
Optical Drives
Typical scenarios:
- Software and media distribution
- Playback of movies and music
- Long-term archival storage
Reason for use:
Optical media is suitable for read-only or infrequently modified data, particularly when physical distribution or long-term preservation is required.
Network Attached Storage (NAS)
Typical scenarios:
- Shared storage in homes, schools, and offices
- Centralised backup systems
- Collaborative work environments
Reason for use:
NAS devices are used when multiple users or devices need shared access to data over a network, providing centralised storage and management.
Summary
- SSDs are used for speed-critical tasks.
- HDDs are used for large, cost-effective storage.
- eMMCs suit low-cost and embedded devices.
- Flash drives and memory cards support portability.
- Optical drives support distribution and archiving.
- NAS systems enable shared, network-based storage.
Different storage technologies are used in different scenarios to balance performance, capacity, cost, portability, and access needs. Understanding these scenarios explains why modern systems often use multiple types of secondary storage simultaneously.
Feature |
Static RAM (SRAM) |
Dynamic RAM (DRAM) |
Memory Type |
Volatile |
Volatile |
Speed |
Faster than DRAM |
Slower compared to SRAM |
Complexity of Design |
More complex; uses six transistors per bit |
Simpler; uses one transistor and one capacitor per bit |
Cost |
More expensive |
Less expensive |
Power Consumption |
Lower; does not need to refresh |
Higher; needs regular refreshing |
Density |
Less dense; occupies more space |
More dense; more memory per chip |
Use |
Used in cache memory |
Used in main memory |
Stability |
More stable; less sensitive to environmental disturbances |
Less stable; sensitive to temperature and electric noise |
Refresh Requirement |
No refresh required |
Constant refreshing needed |
Application |
High-speed applications like CPUs |
Standard memory in computers and other devices |
Secondary Memory Storage | Non-volatile storage used to store data and programs permanently, even when power is removed.
Persistent Storage | Storage that retains data even when power is removed. Secondary memory devices such as SSDs, HDDs, eMMCs, optical media, and network attached storage are all forms of persistent storage
Internal Storage | Secondary storage devices installed inside a computer system and used as the main long-term storage.
External Storage | Secondary storage devices connected to a computer externally, often used for backup, transfer, or shared access.
Solid State Drive (SSD) | A storage device that uses flash memory to store data electronically, providing fast access speeds and high reliability with no moving parts.
Hard Disk Drive (HDD) | A storage device that stores data on rotating magnetic disks using mechanical read/write heads, offering large capacity at lower cost.
Embedded Multimedia Card (eMMC) | A flash-based storage device permanently integrated into a system’s motherboard, commonly used in low-cost and embedded devices.
Optical Drive | A storage device that reads and writes data using laser technology on optical discs such as CDs, DVDs, or Blu-ray discs.
Flash Drive | A small, portable flash-based storage device that connects via USB and is commonly used for file transfer.
Memory Card | A compact flash-based storage device, such as an SD or microSD card, used in portable and embedded devices.
Network Attached Storage (NAS) | A storage system connected to a network that allows multiple users and devices to access shared data.
Non-Volatile Memory | Memory that retains stored data when power is removed.
Read Speed | The rate at which data can be retrieved from a storage device.
Write Speed | The rate at which data can be stored on a storage device.
Storage Capacity | The total amount of data a storage device can hold.
Portability | The ease with which a storage device can be physically moved and connected to different systems.
Backup | A copy of data stored separately to protect against data loss.
Archival Storage | Storage used for long-term preservation of data that is rarely modified.
Persistent Storage | Storage that retains data even when power is removed. Secondary memory devices such as SSDs, HDDs, eMMCs, optical media, and network attached storage are all forms of persistent storage
Internal Storage | Secondary storage devices installed inside a computer system and used as the main long-term storage.
External Storage | Secondary storage devices connected to a computer externally, often used for backup, transfer, or shared access.
Solid State Drive (SSD) | A storage device that uses flash memory to store data electronically, providing fast access speeds and high reliability with no moving parts.
Hard Disk Drive (HDD) | A storage device that stores data on rotating magnetic disks using mechanical read/write heads, offering large capacity at lower cost.
Embedded Multimedia Card (eMMC) | A flash-based storage device permanently integrated into a system’s motherboard, commonly used in low-cost and embedded devices.
Optical Drive | A storage device that reads and writes data using laser technology on optical discs such as CDs, DVDs, or Blu-ray discs.
Flash Drive | A small, portable flash-based storage device that connects via USB and is commonly used for file transfer.
Memory Card | A compact flash-based storage device, such as an SD or microSD card, used in portable and embedded devices.
Network Attached Storage (NAS) | A storage system connected to a network that allows multiple users and devices to access shared data.
Non-Volatile Memory | Memory that retains stored data when power is removed.
Read Speed | The rate at which data can be retrieved from a storage device.
Write Speed | The rate at which data can be stored on a storage device.
Storage Capacity | The total amount of data a storage device can hold.
Portability | The ease with which a storage device can be physically moved and connected to different systems.
Backup | A copy of data stored separately to protect against data loss.
Archival Storage | Storage used for long-term preservation of data that is rarely modified.
- Describe the purpose of secondary memory storage in a computer system.
- Explain the difference between internal and external secondary storage.
- Describe how a solid state drive (SSD) stores data and explain one advantage it has over a hard disk drive (HDD).
- Explain why hard disk drives (HDDs) are often used for large-scale storage despite being slower than SSDs.
- Describe the role of embedded multimedia cards (eMMCs) in computing devices.
- Compare the typical uses of external SSDs and external HDDs.
- Explain why flash drives are suitable for file transfer but not usually used as primary storage devices.
- Describe how network attached storage (NAS) differs from directly connected external storage devices.
- Explain why optical storage is still used in some scenarios despite slower access speeds.
- Using examples, explain how different secondary storage devices are chosen based on performance, cost, and portability requirements.
Sample Answers – A1.1.7 Secondary Memory Storage
1. Purpose of secondary memory storage
Secondary memory storage is used to store data and programs permanently. It retains information when power is removed and provides long-term storage for operating systems, applications, and user files.
2. Internal vs external secondary storage
Internal storage is installed inside a computer system and is typically used as the main long-term storage. External storage is connected externally and is commonly used for backup, data transfer, or shared access.
3. SSD storage and advantage
An SSD stores data using flash memory with no moving parts. One advantage over an HDD is much faster data access speeds.
4. Continued use of HDDs
HDDs are still widely used because they offer large storage capacities at a lower cost per gigabyte, making them suitable for bulk storage and backups.
5. Role of eMMCs
eMMCs provide integrated flash storage for low-cost and embedded devices. They are energy-efficient and compact but offer lower performance than SSDs.
6. External SSDs vs external HDDs
External SSDs are used when fast access and portability are required, while external HDDs are used for large-capacity backups where speed is less critical.
7. Flash drives for file transfer
Flash drives are portable and easy to use, making them suitable for file transfer. They are not commonly used as primary storage due to limited capacity and durability.
8. NAS vs direct external storage
NAS devices connect to a network rather than a single computer and allow multiple users to access shared storage simultaneously.
9. Continued use of optical storage
Optical storage is still used for media distribution and long-term archiving because discs are inexpensive, portable, and resistant to accidental modification.
10. Choosing storage devices
Storage devices are chosen based on requirements such as speed, capacity, cost, portability, and reliability. For example, SSDs are chosen for performance, while HDDs are chosen for affordable large-scale storage.
COMING SOON
A1.1 COMPUTER HARDWARE AND OPERATION
☐ 1.1.1 FUNCTIONS OF THE CPU
☐ 1.1.2 ROLE OF THE GPU
☐ 1.1.3 CPU VS GPU
☐ 1.1.4 PURPOSE AND TYPES OF PRIMARY MEMORY
☐ 1.1.5 FETCH, DECODE AND EXECUTE CYCLE
☐ 1.1.6 PIPELINING IN MULTICORE ARCHITECTURES
➩ 1.1.7 SECONDARY MEMORY STORAGE
☐ 1.1.8 CONCEPTS OF DATA COMPRESSION
☐ 1.1.9 CLOUD COMPUTING
A1.2 DATA REPRESENTATION AND COMPUTER LOGIC
☐ 1.2.1 REPRESENTING DATA
☐ 1.2.2 HOW BINARY IS USED TO STORE DATA
☐ 1.2.3 LOGIC GATES
☐ 1.2.4 TRUTH TABLES, CIRCUITS, EXPRESSIONS AND K MAPS
☐ 1.2.5 LOGIC CIRCUIT DIAGRAMS - COMING SOON
A1.3 OPERATING SYSTEMS AND CONTROL SYSTEMS
☐ 1.3.1 ROLE OF OPERATING SYSTEMS
☐ 1.3.2 FUNCTIONS OF OPERATING SYSTEMS
☐ 1.3.3 APPROACHES TO SCHEDULING
☐ 1.3.4 INTERUPT HANDLING
☐ 1.3.5 MULTITASKING
☐ 1.3.6 CONTROL SYSTEM COMPONENTS
☐ 1.3.7 CONTROL SYSTEM APPLICATIONS
☐ 1.1.1 FUNCTIONS OF THE CPU
☐ 1.1.2 ROLE OF THE GPU
☐ 1.1.3 CPU VS GPU
☐ 1.1.4 PURPOSE AND TYPES OF PRIMARY MEMORY
☐ 1.1.5 FETCH, DECODE AND EXECUTE CYCLE
☐ 1.1.6 PIPELINING IN MULTICORE ARCHITECTURES
➩ 1.1.7 SECONDARY MEMORY STORAGE
☐ 1.1.8 CONCEPTS OF DATA COMPRESSION
☐ 1.1.9 CLOUD COMPUTING
A1.2 DATA REPRESENTATION AND COMPUTER LOGIC
☐ 1.2.1 REPRESENTING DATA
☐ 1.2.2 HOW BINARY IS USED TO STORE DATA
☐ 1.2.3 LOGIC GATES
☐ 1.2.4 TRUTH TABLES, CIRCUITS, EXPRESSIONS AND K MAPS
☐ 1.2.5 LOGIC CIRCUIT DIAGRAMS - COMING SOON
A1.3 OPERATING SYSTEMS AND CONTROL SYSTEMS
☐ 1.3.1 ROLE OF OPERATING SYSTEMS
☐ 1.3.2 FUNCTIONS OF OPERATING SYSTEMS
☐ 1.3.3 APPROACHES TO SCHEDULING
☐ 1.3.4 INTERUPT HANDLING
☐ 1.3.5 MULTITASKING
☐ 1.3.6 CONTROL SYSTEM COMPONENTS
☐ 1.3.7 CONTROL SYSTEM APPLICATIONS
