3.5 Memory & Storage Flashcards
Primary storage
Storage inside the processor
Random Access Memory (RAM)
- Works by storing data as electrical charges
- Volatile - charges disappear when electricity is switched off
- CPU can access data in RAM very quickly
- Read and write
What does RAM store?
- Operating systems
- Running programs
- Data currently being used
Read-only Memory (ROM)
- Small area of non-volatile memory
2. Read-only
What does ROM store?
Computing boot up instructions (Bootstrap)
Volatile memory
Memory that loses its contents when the electricity is turned off
Secondary storage
Storage outside the processor
Explain what is meant by off-line storage.
- it is non-volatile
- can be easily disconnected from the computer
- it is not directly accessed by the CPU
- suitable example eg. CD, DVD, USB flash memory
Secondary storage
Magnetic storage - Hard Disk Drive (HDD) pros
- Wired directly to processor, so access to HDD is quite fast (fast write speed)
- Cheap
- Vast storage capability, up to 2 TB or more
Secondary storage
Magnetic storage - Hard Disk Drive (HDD) cons
- Lots of mechanical parts
- Not very durable
- Internal hard drive is fixed inside a computer, so it is not portable
- Makes spinning disc sounds
Off-line storage
Magnetic storage - Portable hard disk / removable HDD
Must be plugged into the computer through a port (functions like a HDD)
Off-line storage
Magnetic storage - Magnetic tape pros
- Large capacity
- Inexpensive
- Does not take up much storage space
Off-line storage
Magnetic storage - Magnetic tape cons
Slow to transfer data, because you need to wind through the whole reel of tape to get to the data you want
Off-line storage
Optical storage - Why can a DVD store more data than a CD?
- The pits are smaller
2. Read with a narrower laser spot (red laser light) than is used for a CD
Off-line storage
Optical storage - Why can a Blu-ray disc store more data than a CD/DVD?
- The pits are even smaller than that of a DVD
2. Read with an even narrower laser spot (blue laser light) than is used for a DVD
Off-line storage
Optical storage - DVD-RAM
It has concentric tracks (instead of a single spiral track) allowing reading and writing to take place simultaneously
Secondary storage
Solid state storage/flash memory - 6 Solid state drive (SSD) pros
- Data access is fast (can replace a computer’s built-in HDD, because data is very close to the CPU)
- Run quieter (no noisy fan)
- Highly durable and reliable because no moving parts, so more suitable for portable computer/laptop
- Run cooler
- Less power consumption
- Large storage for its size - therefore used in many mobile devices
Secondary storage
Solid state storage/flash memory - Solid state drive (SSD) cons
Expensive
Off-line storage
Solid state storage/flash memory - USB flash memory/ drive
- A flash memory IC (integrated circuit) in a USB plug
- Low cost
- Portable and has no moving parts
- Durable
- Holds a lot of data for its size
5 reasons for choosing magnetic storage over solid state storage
- more read/write cycles over its lifetime / greater longevity
- read/write speed is sufficient for most applications even though it is slower than solid-state
- cheaper PER UNIT OF DATA stored
- trusted technology as it has been traditionally used for many years
- no requirement for portability
