Fundamentals of Computer Organisation and Architecture Flashcards
What is RFID?
Stands for Radio Frequency Identification.
A method of transferring information wirelessly between a tag and a reader.
Explain how a RFID tag could be read at passport control at an airport:
- RFID scanner/reader at passport control transmits/sends a signal;
- signal induces current/activates RFID tag;
- RFID transmits data by radio waves;
- Electrical/physical contact between tag and reader not necessary;
- Passport may need to be unlocked using machine readable zone/key
How does RFID generally work?
Stage 1: When a RFID tag is scanned, the reader emits radio waves which are picked up by the tag’s antenna.
Stage 2: The power induced in the tag’s antenna is enough to power the chip.
Stage 3: The chip then uses its antenna to emit its own radio waves, which contains information held on the chip.
This wave is picked up by the
reader which decodes the information and returns the information to a computer.
How does active RFID work?
Active RFID systems use battery-powered RFID tags that continuously broadcast their own signal.
Active tags contain a small power supply like a battery. Active tags can be used much further away from readers than
passive tags which must be held within a few centimeters of their reader.
How does passive RFID work?
They induce enough power wirelessly from the reader to operate the chip
What is a Solid State Drive?
A solid state drive is a secondary storage device consisting of NAND flash memory and a controller that stores data electronically with no moving parts.
How does a SSD work?
NAND flash memory is non-volatile meaning that the SSD’s contents are retained even when there is no power being supplied.
The memory gates are formed of floating gate transistors which stores information by trapping electrical charge.
Data is stored on SSD’s in pages, which are combined to form blocks.
SSD’s are not able to overwrite data, instead the controller must completely erase a page before writing new information to it.
Capable of higher read and write speeds than HDD’s as SSD’s don’t have any moving parts. Suitable for use in portable devices such as phones and tablets.
What is cache?
small amounts of memory that’s close to the CPU
What is cache used for?
quick access to frequently used commands
What is the impact of increasing cache?
overall fetch, decode, execute process speeds up
What is on-chip cache?
cache physically built into the microprocessor
What is virtual cache?
CPU takes over RAM to act as virtual cache memory. Due to RAM’s extremely high read and write rates, it acts very similarly to normal cache and can be used for files that are required urgently, but of less priority than those stored in the main cache.
What is Level 1 Cache?
L1 cache has extremely fast transfer rates, but is very small in size. The processor uses L1 cache to hold the most frequently used instructions and data. Can be embedded on the CPU or exist as a separated chip.
What is Level 2 Cache?
L2 cache is considered as slower memory than level 1 cache as data stored in this memory is temporarily stored but the storage capacity is larger. level 2 cache is a secondary type of cache memory and is located on a computer microprocessor.
