Activities pg 145

nREMEMBER
1. Random Access: That any storage location can be directly read or written.
* It is also called "direct access"
 Storage device:
-DVD
-USB Memory Device
-Hard Disk Drives
2.Sequential Access: That any storage locations have to be read or written in their correct order, starting with the first location.
Storage Device:
- Tape
3. Volatile: Storage devices that will lose all their data is the power is switched off.
- RAM not volatile

THINK
4. RAM is the only volatile storage device as it needs a constant power supply to keep its data.
- Refreshed

- SSD ( Sold State Drives): Instead of using hard disk drive, they use flash memory. They are secondary storage, form role of hard disk, but use flash memory. They are not removable
Advantages:
- Fast
- No moving parts, thereby don't tend to crash.
- No motor to fail
- No read write head to crash

- How long can they last?
- Solid State Drive: Like having memory sticks within the computer.
- Solid State Drive good for cameras, due to the environment cameras are used in.

* Hard Disk Drive: Motor which spins the disk, 7000 revolutions/minute. Floating above it, delicate wafer, devices that can magnetic fields and generate magnetic field. Disk has ion compound and can be ionised. Can read magnetic patterns of disk.
* Read write head, crashes onto the surface: it destroys the surface, regions on the disk that are corrupt. Not hard to corrupt hard disk.
5. Sequential access devices are better suited for storing backup data due to [its speed problem.]
Note: It is the slowest, especially if data is at the other end of the tape.
- there are tape systems which record the position of every file on the tape.
- it then uses fast forward and fast rewind to move quickly to the file.
- in saying this their speed is significantly slower than disk access.
Therefore better suited for storing back up data as well as long term data storage.