Data Storage Flashcards
(25 cards)
What is primary storage?
Primary storage is directly accessed by the CPU.
Characteristics of Primary storage
- Volatile (with the exception or ROM)
- Small Capacity
Characteristics of Secondary storage
- Non-volatile
- Large Capacity
Why do you need primary storage?
- A computer needs primary storage because access times are considerably faster than secondary
- This means the time taken to complete operations such as the Fetch-Execute Cycle is dramatically reduced
Characteristics of RAM (Random Access Memory)
- Primary storage directly connected to the CPU.
- Holds data and instructions currently in use.
- Volatile contents are lost when power is off.
- Data must be copied from secondary storage
- Read/write memory data can be read and written.
- Has a much larger capacity than ROM
Characteristics of ROM (Read Only Memory)
- ROM (Read Only Memory) is primary storage that stored boot up instructions
- ROM contains the BIOS (Basic Input Output System)
- ROM is a small memory chip located on the computers motherboard
- ROM is fast memory, much faster than secondary storage but slower than RAM
- ROM is non-volatile
- ROM is read only which means data can only be read from
What are the three types of secondary storage?
- Magnetic
- Solid-state (flash memory)
- Optical
What is secondary storage?
A computer needs secondary storage for long term storage of programs and data that are currently not in use and is needed since ROM is read only and RAM is volatile
Characteristics of Magnetic Storage
- Data is stored on platters
- Platters are divided into tracks and sectors
- Data is read using a read / write arm
- Data is read / written using electromagnets
- It is non - volatile
Characteristics of Solids State Storage (SSD)
- Can be volatile or non-volatile
- Flashes data onto chips
- Uses transistors
- Uses NAND / NOR technology
- Uses control and flow gates
- Controls the flow of electrons
Examples of Magnetic Storage
- HDD
- Floppy Disk
- Magnetic Tape
- Magnetic Strip
Examples of Solid State Storage
- SSD
- USB Drive
- SD Card
- RAM
Examples of Optical Storage
- CD
- DVD
- Blu - Ray
How does optical storage work?
- Laser is shone at the disk
- An arm moves the laser across the surface of the disk
- The laser burns pits onto the disk surface
- The laser is used to read the pits and lands
- The reflected light from the laser shining on the disk is captured by a sensor.
Describe how a magnetic storage device stores data.
- Storage device has platters
- Platters/disk divided into tracks
- Storage platter / disk is spun
- Has a read/write arm that moves across storage media
- Read/writes data using electromagnets
- Uses magnetic fields to control magnetic dots of data
- Magnetic field determines binary value
Advantages of Solid State Storage
- It is small in size // compact // lightweight // portable
- It has low power consumption
- It runs quietly
- It runs at a cool temperature
- It is robust when dropped // durable
- Fast access/read/write speed
- High capacity
- Not affected by magnets
Disadvantages of Solid State Storage
- Reliability - Limited read and write cycles
- Cost is very high per GB
Advantages of Magnetic Storage
- High storage capacity
- Low cost per gigabyte
- Moderate read and write speeds
Disadvantages of Magnetic Storage
- Durability - Moving parts can get damaged if dropped
- Portability - Heavy & bulky making them less convenient for transport
- Reliability - Prone to mechanical failure
- Noise - Loud (spinning disks)
Advantages of Optical Storage
- Cost: Very low per gigabyte
- Durability: No moving parts
- Portability: Small and no moving parts
- Noise: Silent
Disadvantages of Optical Storage
- Capacity: Very low
- Speed: Very slow read/write access
- Reliability: Prone to scratches
Explain how virtual memory works
- Virtual memory is an extension of primary storage (RAM) located on secondary storage
- In situations where RAM is close to being full, virtual memory can be used so that the computer remains operational
- Programs and data not currently being executed are transferred to virtual memory
- Programs and data are transferred back to RAM when they are needed
- Programs are stored as pages of data
- Pages of data are transferred between RAM and virtual memory when needed
- Virtual memory is much slower than RAM and its use will impact negatively on system performance
- To avoid the use of virtual memory, increase the size of the RAM
Disadvantages of cloud storage
- May be less secure
- May lose access if internet connection is lost
- Reliant on a third party maintaining the hardware
- Could incur an ongoing fee
State the meaning of cloud storage
- A collection of servers
- That store data in a remote location
- That are accessed using an internet connection
