central processing unit architecture Flashcards
AS-level (36 cards)
purpose and roles of the control unit
–directs and co-ordinates other parts of computer system
–controls operations of computer system
–fetches computer instructions
–decodes each instructions
–executes these instruction.
purpose and roles arithmetic logic unit
– a unit which performs arithmetic operations
–and bit shifting operations
– logic operation(AND,OR,XOR)
–designed to perform integer calculation
define operand
part of the computer instruction which specifies what data is to be processed
define opcode
is the instruction that is executed by the cpu
purpose and role of registers
–small piece of memory
–part of the processor
–temporary storage of data which is about to or had been processed
difference between general purpose and special purpose registers
general purpose registers holds the temporary data while performing difference operations.
special purpose registers holds the status of a program
define program counter
stores the address of next instruction to be fetched
define MAR
stores memory address where data is to be read from
define MDR
stores data that has just been read from memory
define CIR
stores the instruction that is currently being executed
define IX
index register used for indirect addressing .
define ACC
(accumulator) is the register where the data is worked on (general purpose register).
define status register
is interpreted as independent flags each flag is set depending on an event .
purpose and role of a system clock
–every computer contains an internal clock that regulates the rate at which the instruction are executed
–CPU requires a fixed number of clocks cycles that executes each instructions
– used to synchronize all the operation.
state the various components of the computer system that transfers data
–data bus
–address bus
–control bus
define data bus
–carries data between processor and memory
–bi-directional bus
– used to exchange data
define address bus
–uni- directional
–that carries signal related to memory address
– between processor and memory
define control bus
–transmits signals between control unit and other components
–bi-directional
what are the factors affecting the computer performance
–data bus width
–clock speed
–cache memory
–number of cores
define how the data bus width affects performance
– the width of a bus determines the number of bits that can be simultaneously transferred
–increasing the width of a data bus increases the number of bits that can be transferred
– hence improve processing speed as fewer transfers are needed
define how the clock speed affects performance
–one F-E cycle is run on each clock pulse
–so the clock speed dictates the number of instructions that can be run per second
–the faster the clock speed the more instructions can be run per second
define how the cache memory affects performance
can also improve processor performance , it is similar to RAM, cache uses SRAM so they have faster access time as there is no need to keep refreshing. cache memory stores frequently used instructions and data that needs to be accessed faster , this improves processor performance
define how the number of cores affects performance
–each core processes one instruction per clock pulse
–more cores mean that sequence of instructions can be split between them and so more than one instruction is executes per clock pulse
–more cores decreases the time taken to complete task
define a port
acts as an interference between computers and other peripheral devices. female part of connection
