1.1.3 Input, output and storage Flashcards
(a) How different input, output and storage devices can be applied to the solution of different problems. (b) The uses of magnetic, flash and optical storage devices. (c) RAM and ROM. (d) Virtual storage.
What is an actuator?
A motor used in conjunction with sensors in order to control a mechanism.
How does a hard disk work? (Magnetic storage)
A hard disk has a rotating platter covered in magnetic material, the magnetic particles on the disk are polarised to be either north or south in order to represent 1 and 0. The disk is divided into concentric circles which are tracks, each track is subdivided into sectors and data is stored in various different sectors. Data is read by the read/write head as the disk passes under the read/write head and data is written by changing the polarity in certain sectors.
What is the advantage and disadvantage of magnetic storage?
The advantage is that they have a huge capacity making them suitable for desktop purposes.
The disadvantage is that they are not very portable.
How does an optical disk work? CD-RW (Optical storage)
An Optical disk works by using a high powered laser to burn sections of its surface in order to make them less reflective, a laser at a lower power reads data by pointing it at the disk and a sensor is used to measure how much light is reflected back.
What are the three types of optical storage?
CD-ROM, CD-RW, CD-R
What is the advantage and disadvantage of optical storage?
The advantage is that optical storage is very cheap to produce and easy to mail for distribution purposes.
The disadvantage is that data can be easily corrupted by damaging the surface of the disk.
How does an SSD work? (Flash storage)
an SSD is comprised of millions of NAND flash memory cells, each cell works by delivering a current along the bit and word lines to activate the flow of electrons from the source to the drain. the current along the word line is strong enough to force some electrons upwards into a floating gate where once the current is shut off they trapped. if there is charge in the floating gate the cell is considered a 0 if not, it’s a 1.
What is the advantage and disadvantage of flash storage?
The advantage is SSD’s are less susceptible to damage due to the lack of moving parts.
The disadvantage is that SSD’s have a low capacity and are expensive.
What is ROM?
Read-only memory. used to hold information needed permanently in memory (bootstrap loader).
What is RAM?
Random access memory, a form of primary memory used to hold data/programs in use.
What is the difference between RAM and ROM?
RAM has volatile memory, meaning all data is lost once power is lost, ROM is not volatile and data is retained after power is lost.
What is meant by virtual storage?
When the hard disk is used as an extension of main memory.
How does virtual storage work?
The operating system uses an area of secondary storage as virtual memory.
- Move unused pages/parts (of program A and/or
B) into virtual memory
- Load program C into (physical) memory.
