Year 1 1 cpu - virtual memory, storage

• Computing
• Upper Secondary (Key Stage 4)
• GCSE

Year 1 1 cpu - virtual memory, storage

Virtual memory

Computers have a fixed amount of RAM, what happens when that space runs out?

• Computers need somewhere to put current used applications.

• These are placed in secondary storage to prevent computers from crashing. This is called paging

• The applications currently in view are switched back into RAM, this takes time and is a slow process.

Secondary storage

Secondary storage refers to any non-volatile storage medium that stores data until it is deleted or overwritten. 

There are 3 types of secondary storage : Magnetic (HDD), Solid State (SSD), Optical (CD/DVD).

Magnetic storage

Magnetic storage, one of the oldest types of secondary storage, uses magnetic fields to record data. The most common example is the hard disk drive (HDD). An HDD consists of one or more platters coated with a magnetic material. Data is written to and read from the platters by a read/write head that moves across the disk's surface.

Advantages:

• High Capacity: HDDs offer large storage capacities at a relatively low cost, making them ideal for storing vast amounts of data.
  
• Cost-Effective: Due to their mature technology, HDDs provide a cost-efficient solution for extensive data storage needs.

Disadvantages:

• Slower Speed: Compared to newer technologies like SSDs, HDDs have slower data access speeds.
• Mechanical Parts: The presence of moving parts makes HDDs more prone to mechanical failure and physical damage.
  

Use Cases:

• HDDs are commonly used in desktops, servers, and for backup solutions where high capacity and low cost are prioritized over speed.

Optical storage

Optical storage uses lasers to read and write data on discs made of plastic with a reflective coating. Common types of optical storage include CDs (Compact Discs), DVDs (Digital Versatile Discs), and Blu-ray discs. Data is encoded in the form of tiny pits and lands on the surface of the disc, which are interpreted by the laser.

Advantages:

• Durability: Optical discs are resistant to environmental factors like dust, water, and temperature changes, making them suitable for long-term data archiving.
  
• Portability: They are lightweight and easy to transport, which is useful for sharing data and media.
  

Disadvantages:

• Limited Capacity: Compared to magnetic and solid-state storage, optical discs have lower storage capacities.
  
• Slower Access: Reading and writing data on optical discs is generally slower than other types of secondary storage.
  

Use Cases:

• Optical storage is frequently used for distributing software, movies, and music, as well as for creating backup copies of important data.

Solid state

Solid-state storage, such as solid-state drives (SSDs) and USB flash drives, uses flash memory to store data. This technology relies on electrically programmable memory cells, which retain data even when the device is powered off. SSDs do not have moving parts, which distinguishes them from HDDs.

Advantages:

• High Speed: SSDs offer significantly faster data access and transfer speeds compared to HDDs, resulting in quicker boot times and improved performance.
  
• Durability: The absence of moving parts makes SSDs more resistant to physical shock and vibration, reducing the risk of mechanical failure.
  

Disadvantages:

• Cost: SSDs are more expensive per gigabyte than HDDs, though prices have decreased.
  
• Finite Write Cycles: Flash memory cells have a limited number of write cycles, although this limitation is being mitigated by advancements in technology.
  

Use Cases:

• SSDs are commonly used in laptops, desktops, and high-performance systems where speed and reliability are critical. USB flash drives are popular for their portability and convenience in transferring files between devices.

A school needs to archive student reports from the last 10 years.
A gamer wants fast load times when playing games on their PC.
A musician wants to distribute an album physically to fans.
A user wants a large but cheap storage solution for home backups.
A software developer installs an operating system on a new laptop.

HDD

HDD

SSD

SSD

OPTICAL DISC

High speed, no moving parts
Cheapest per GB
Prone to scratching or physical damage
Commonly used in modern laptops and smartphones
Slower access time due to mechanical components

HDD

HDD

SSD

SSD

OPTICAL DISC

Exam question:

A student is creating a presentation containing images and sound.

The student wants to use a secondary storage device to move their files to their home computer.

Identify whether the student should use an optical or solid-state type of secondary storage device. Justify your choice.

Optical or solid-state ………………………………

Justification...................................