Secondary storage

Question 1

What is the need for a secondary storage within a computer system?

Answer 1

Because the main memory is normally either ROM (Read only) or RAM (volatile)

Needed for storage of program and data when power is turned off

backup data, archive,

Question 2

How do magnetic hard disks work?

Answer 2

Binary digits are represented by magnetic spots on the disk.
The disk is made up of platters, which is divided into tracks and sectors.
Disk spins at high speed, and data is read/written as correct sectors passes under the read/write head

Question 3

Assess the suitability of magnetic hard disks

Answer 3

Cheap, high capacity

Moving parts, maybe slower

Question 4

How can the storage of a hard disk be increased?

Answer 4

More platters;
Greater density of data on each platter;
More tracks on platter;

Question 5

How do optical disks work?

Answer 5

Flat circular disk;
Binary data is encoded in the form of pits and lands;
High power laser burns pits;
Low power laser reads pits and lands;

Question 6

Assess the suitability of optical disks

Answer 6

Can be easily scratched;
Low capacity;
Very cheap;
Very portable;

Question 7

How do SSDs work?

Answer 7

Solid-state disks are made up of a controller and a bank of millions of NAND ‘flash’ memory cells;
Each cell has a floating gate transistor that allows an electrical charge to be trapped;
A charged cell represents a 0, and a cell with no trapped charge represents a 1;

Question 8

Asssess the suitabilty of SSDs

Answer 8

Faster;
More robust;
Lighter;
Expensive;