4.7 Fundamentals of computer organisation and architecture Flashcards
Explain the difference between von Neumann and Harvard architecture
Von Neumann:
Instructions and data are both stored in main memory
Both pass through the same bus in and out of memory
Harvard:
Separate buses for data and instructions, both of which address different parts of memory
Where is harvard architecture used?
Used in small embedded computers and signal processing (DSP).
Where is von nuemann used?
Desktop computers, laptops etc…
What is the stored program concept?
Machine code instructions stored in main memory are fetched and executed serially by a processor that performs arithmetic and logical operations
What is the benefit of Harvard architecture?
The performance benefits due to increased bandwidth and Harvard architecture machines find use in high performance embedded applications like Digital Signal Processing.
What methods of error detection exist for barcodes?
Parity bits and check digits are used to tell if the barcode is correct
What is RFID?
RFID (radio frequency identification), is a method of transferring information
wirelessly between a tag and a reader. Most are passive and gain energy from the reader.
When scanned they emit radio waves which are picked up by the tags antenna. The power
What is a hard disk drive?
A storage method with multiple circular platters made from a magnetic material. Each platter is read by
an actuating arm which has a read/write head. This head changes the polarity of parts of the platter.
Data is written in tracks which are divided into sections. It rotates thousands of times a second, allowing for good read/write speeds.
What does a solid state drive contain?
A storage method which involves NAND flash memory and a controller to manage the structure of data in the drive.
what do barcode readers contain? what do they do?
a laser light source, a lens, photodiodes and a mirror.
Mirror reflects light from laser onto the barcode.
The light reflected passes through the lens to a photodiode where it is converted to an electrical
signal representing the content of the barcode.
what are the types of barcode?
1d and 2d, 2d takes more processing to read but store information more densely.
What are the advantages/disadvantage of solid state memory over a hard disk drive?
advantages:
- quiet/ portable/ light
- not susceptible to damage from movement
- no moving parts so high read/write speeds
- more energy efficient
disadvantages:
- shorter lifespan, only limited number of read/writes
- cost, more expensive
- less storage space
How does a digital camera work?
1) Digital cameras consist of a lens that focuses light onto a sensor.
2) The path of light between the lens and the sensor is regulated by a shutter.
3) Two sensors commonly used in digital cameras are CMOS (complementary metal oxide semiconductor) and CCD (charge coupled device) which both convert incident light into electrical charge.
4) Charge builds up in cells, each of which represents a pixel in the image.
5) Once the photograph has been taken, the charge in each of the cells is measured and
converted to a digital value which is then processed by the camera and stored as a digital image.
How are optical disks read?
Optical disks have one continuous track. A low power laser is reflected into a photodiode which reads either light 1 or dark 0.
What are the types of optical disks?
CD/DVD/Blu-ray store information which is read optically by a laser. Can be Read only, recordable or rewritable.
Read only disks have pits which are burned into a disk by a high power laser which permanently deforms the surface.
Rewritable and recordable disks use a non-opaque dye which is used to prevent reflecting back the laser light.
Recordable disks use a laser and a magnet to heat a spot and change its polarity.
