Section 5 Computer Orginisation and Architecture Flashcards
what is the fde cycle
fetch decode execute cycle
what happens in the fetch part of frhe cycle ?
causes the next instruction to be fetched from main memory
what happens during the decode part of the cycle
the instruction is decoded
what is the alu
arithmetic logic unit
performs different sorts of operations on data such as addition subtraction multipilication and division.
what is the cu?
control unit , regulates and intergrates the operations of the computer/ controls and coordinates the activities of the cpu
what is a bus ?
a set of parallel wires connecting two or more compoments of a computer
what are the three busses ?
control bus
data bus
address bus
what is the control bus ?
a bi diectional bus that transmits commands , timings and specific status information between system compoments
what is the data bus ?
a bus that provides a bi directional path for moving data and instructions between system compoments
what is the address bus ?
a bus that identifies the location in cache or main memory that is to be read or written to
the width of what bus determines overall system performance ?
data bus
the width of what bus determines the maximum possible memory capacity of the system ?
address bus
what are I/O controllers?
a device which interfaces between an input or output device and the processor
what is an interface ?
a standardised form of connecting defining things as signals , number of connecting pins and voltage levels
explain the von neumann architecture ?
the basic compoments of the computer and processor in which a shared memory and bus is used for both data and instructions
what is the stored program concept
machine code instructions are fetched and executed serially by a processor that performs arithmetic and logical operations
explain the harvard architecture
a computer atchotecture with phycially seperate memories for instructions and data
what is the system clock ?
generates a series of signals , switching between 1 and 0 billions of times per second and synchronising cpu operations
what is the accumilator ?
what is a PC ?
program counter , holds the address of the next instruction to be executed
what is fhe CIR ?
current instruction register , holds current instruction being executed
what is the mar?
memory address register , holds address of the memory location from which data is to be fetched
what is the mbr ?
memory buffer register , temporarily stores data read from or written to memory
what is the status register?
contains bits that are set or cleared depending on the result of an instruction
factors affecting processor performance
- number of cores
- the amount and type of cache memory
- clock speed
- word legnth
- adsress bus width
- data bus width
explain the fetch phase of the fde cycle
address of next instruction copied from PC to MAR , sent via address bus to main memory
instruction held at address is returned along the data bus to MBR
the content of the MBR is copied to CIR
explain the decode phase of the cycle
intruction held at CIR is decoded
instruction split into opcode and opcode is used to deterine the type of instruction
explain the execute phase of the cycle
instruction is executed
what is level 1 cache
extremely small but fast memory
between 2 - 64 kb
what is level 2 cache
failry fast and medium sized memory
256kb - 2mb
how does a digital camera work?
uses ccd or cmos sensor comprising millions of tiny light sensors arranged ina grid
when the shutter opens light eneter camera
each sensor measures the birghtness of each pixle
these are then later ocnverted into binary and then displayed on the screen of the digital camera
how do RFID tags work?
these are small tags that release radio waves at a given frequency which can be read from up to 300m
what is an active RFID tag
tags that include a battery to power the tag so that it actively transmits a signal for a reader to pick up
what is a passive RFID tag
do not have a battery, rely on radio waves emitted from a reader up to a meter away to provide sufficient electromagnetic power to the card using its coiled antena
how does a laser printer work
printer generates a bitmap image of the printed page and using a laser unit and mirror draws a negative , reverse image onto a negatively charged drum
the laser light causes the affected areas of the drum to lose their charge.
the drum rotates past a toner hopper to attract charged toner particles onto the areas which have not been lasered
what is the need of secondary storage ?
retains its content when the conmputers power is turned off so that the user is able to store data / files on their computer
name all of the parts of a hard disk ?
read / write head
track
sector
platters
how does optical storage work
whilst the disk is spinning a laser is shone onto the disk. this laser is able to detect where there are flats and dips. these flats and dips are later converted into binary which then allows the computer to be able to read the data
what is a SSD
a form of secondart storage that uses electrical impulses to store data
