it hardware Flashcards
what are the main sections of the CPU?
the Control unit(CU) and the Arithmetic Logic Unit ( ALU)
what do the ALU and CU contain?
registers
what is the function of the CU?
it controls the execution of each instruction and sends read or write signals to memory and the address of the instruction to be fetched
what is the function of the ALU?
calculations and logical comparisons take place here. Once processed data results may be sent back to memory to be stored there.
what is the accumulator?
it is a register that stores the result of each execution.
what happens when data is stored?
its written from the accumulator to RAM.
what is the function of registers?
they store the current instruction and its data
what are registers made of?
static RAM or (SRAM)
why is SRAM so fast?
they do not contain capacitors. Which have to be constantly refreshed.
How many bits are in CPU registers?
32 or 64 bits
what is the difference between 32 bit processors and 64 bit processors.
32 bit processors have to process information in two stages where as 64 bit processors do so in one stage which improves their performance.
what does paralell processing do?
a method of simultaneously breaking up and running program instructions on multiple multiprocessors.
how does parallel processing work?
Each part is broken into its individual set of instructions and each instruction on a different processor or if a user is running different programs at the same time each program can be run on its own processor
how does hyperthreading work?
by duplicating registers on the chip the next instruction is preloaded into the second set of registers while the first set of registers is being processed reducing the time it took to switch between instructions
what does hyperthreading allow for?
hyperthreading makes it appear as if two sets of instructions are being executed at the same time.
what is a set of instructions called?
A thread
what is the entire program to be processed called?
A process.
what is a process state?
All values related to the process that are stored in the registers.
where is the data of the currently executing instruction saved?
In RAM
where is the state or data of the next process loaded?
from RAM to the registers
how does hyperthreading improve performance?
it allows for fast context switching between two processes eliminating the time of loading and saving into the registers each time there is a switch between processes.
what does a hyperthreaded CPU appear as in the Operating System?
two logical CPU where in actuality there is only one physical CPU with two sets of registers.
what is the important thing to remember about hyperthreading and Operating Systems?
Hyperthreading must be supported by the Operating System.
what is multiprocessing?
It is having multiple CPU called cores on a single CPU chip.
what does multiprocessing change from hyperthreading ?
it allows for multiple processes multiple to happen at the same time instead of appearing to happen at the same time.
what must support multiprocessing for it to be effective?
it must be supported by the motherboard and the operating system.
what effects the perfomance of the CPU?
The speed of the CPU and the register size.
what is the general rule of the CPU?
It should never stay idle.
what is between the CPU and RAM
cache memory
what is cache memory made of ?
SRAM which is faster than DRAM(Dynamic RAM which is normal RAM.
what does cache do?
stores blocks of program instructions and data that have been pre- fetched from RAM in hope that these instructions or data will be needed next by the CPU.
what is level one cache ?And how fast is it?
it is a small amount of memory built into the internal circuitry of the CPU. it is usually the same speed as the CPU’s internal speed.
what is level two cache, where is it and how fast is it?
it can be located on the CPU chip it is usually half the CPU speed and it is larger than level one
what is level two cache, where is it and how fast is it?
it can be located on the CPU chip slightly further away from the internal CPU circuits, L2 is usually slightly larger and usually slower access running at about half of the CPU’s internal speed.
where is level 3 cache located and how fast is it:?
it is on the motherboard closer to the CPU and RAM. It is larger and slower access than L! and L@
In which order does the CPU check cache before it checks RAM?
L1 then L2 and then L3 and finally RAM.
how is cache incorporated on modern CPU’s?
most modern CPU’s have built in L1 and L2 caches per core and share a single L3 cache on the motheboard while other designs have the L3 on the CPU die itself.
what is a cache hit and a cache miss?
This is when the requested data can be found in a cache while a cache miss occurs when it cannot.
how are cache hits served?
when the data is read from cache.
how does cache improve performance ?
when more requests can be served from the cache .
what does RAM do?
RAM stores the programs currently in use and the data associated with them.
what does RAM
do?
RAM stores the programs currently in use and the data associated with them.
what is the most common type of RAM?
Double Data Rate SDRAM
what does each DRAM chip contain?
a capacitor.
what does SDRAM stand for?
Synchronous Dynamic Read Access Memory.
What is synchronised with the CPU and why?
the refreshing of the RAM chips is synchronised with the CPU so that the CPU does not have to wait while refreshing takes place.
why does synchronising the CPU and the refreshing of the RAM improve performance?
The CPU is working at a very high frrequency and instructions can be fed to the CPU at a fast rate reducing the length of time that the CPU is idle.
what does Double Data Rate mean?
It means that data is tranferred twice as fast as when data was transferred only once every clock pulse.
what is latency?
its the time taken for a component to respond.
what is latency measured in?
clock ticks.
what are the different levels of memory?
level 0: registers
level 1 : on chip L1 cache(SRAM)
level 2:off chip L2 cache chip (SRAM)
level 3: main memory(DRAM)
level 4 local secondary storage(local disks)
level 5: remote secondary storage ( distributed file systems, Web servers)
what is the motherboard?
it is the central printed circuit board that connects components and devices to each other.
what connect components and devices?
busses
what are the slots on the motherboard for?
to connect devices like graphic cards and hard drives.
what is a system clock?
the clock refers to a microchip that regulates the timing and speed of all computer functions.
how does a system clock work?
there is a crystal that vibrates at a specific frequency when electricity is applied.
what is the shortest time any computer component can perform at?
one clock or one vibration of the clock chip.
what is overclocking?
this is the practice of making computer components run at speeds father than designed by manipulating the frequencies at which the component is set to run .
what are the two ways overclocking can be performed?
per component which means the CPU operates faster than the system clock by changing its own manipulation factor.
the whole system the system clock is increased affecting all components that detect the system clock and multiply by a factor.
what is clock multiplication?
increasing the clock multiplier
what is the danger of overclocking?
the components may run faster than the speed for which they were designed and tested causing them to become unstable or fail,
what is CPU speed measured in ?
GHz
what is RAM speed measured in?
MHz