COMPUTER ORGANISATION | COMPUTER ARCHITECTURE

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SECTION 1 | SECONDARY STORAGE
SECTION 2 | PERSISTANT STORAGE

ALSO IN THIS TOPIC
 COMPUTER ARCHITECTURE
 YOU ARE HERE | SECONDARY MEMORY
OPERATING SYSTEMS
BINARY REPRESENTATION
LOGIC GATES
TOPIC 2 REVISION | NEW
KEY TERMINOLOGY
TOPIC 2 ANSWERS

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Topics from the International Baccalaureate (IB) 2014 Computer Science Guide. 

SECTION 1 | SECONDARY STORAGE

Secondary storage, also known as external or auxiliary storage, refers to a type of computer storage that is used for long-term data storage. Secondary storage devices are used to store data and programs that are not currently being used or accessed by the computer's CPU (Central Processing Unit).

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:

1. Hard disk drives (HDD)
2. Solid-state drives (SSD)
3. Optical discs (CD, DVD, Blu-ray)
4. USB flash drives
5. Memory cards (SD, microSD)
6. Magnetic tapes
7. External hard drives
8. Network-attached storage (NAS) devices
9. Cloud storage services.

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Overall, 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.

SECTION 2 | PERSISTANT STORAGE

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.
Overall, 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.

​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

ALSO IN THIS TOPIC

COMPUTER ARCHITECTURE
SECONDARY MEMORY
OPERATING SYSTEMS
BINARY REPRESENTATION
LOGIC GATES
TOPIC 2 REVISION | NEW
KEY TERMINOLOGY
TOPIC 2 ANSWERS