1.1.1 Structure and Function of Processor Flashcards
CPU’s job?
cpu processes data and instructions. cpu is where all searching,calculating,sorting and decision making takes place
what does the CU stand for?
Control Unit
function of the CU?
to manage execution of instructions.
controls and monitors hardware
controls input and output of data(so signals go to the right place at the right time)
controls flow of data in CPU
what is used for signal sending ?
buses
what is the ALU responsible for ?
responsible for performing mathematical calculations and logic operations. Also it acts as a gateway to processor
where are results from ALU stored?
accumulator
what is a register ?
a high speed storage area in the CPU used for instruction processing
what are the 5 registers ?
PC MAR MDR CIR ACC
what does CIR stand for ?
current instruction register
role of the PC (program counter)
contains address of the next instruction to be executed
function of MAR
stores memory address from which data will be fetched or sent and stored
function of MDR
stores data being transferred to and from access storage
function of CIR
contains information specifying the instruction tags being or about to be performed
function of ACC
stores ALU calculations
what are buses ?
pathways used to send data around the processor
what are the 3 main buses ?
control
data
address
characteristics of a control bus
it is used by CPU to communicate with other devices and components carrying commands and returning status signals
characteristics of a data bus
carries data/information from one register to the other between the processor and the memory
characteristics of an address bus
carries the address of the memory location being read or written to
what bus would be used between the CPU and main memory when MAR needs the instruction address
address bus
what bus would be used to get the instruction data to MDR from main memory
a data bus
what bus would be used between acc and the main memory after instruction execution
control bus
FETCH
PC holds address of next instruction. Address is copied to MAR Location is sent down address bus and fetch signal is sent by control bus Contents from memory go to processor Contents in MDR and then copied to CIR PC increments by 1
DECODE
CIR contents go to control unit
CU does the decoding.
- it also checks against set of instructions in ROM within CPU
Check is preformed to make sure data is present for current instruction (in MDR)
EXECUTE
Instruction address copied from CIR to MAR
Processor carries out instruction.
Return result into L1 data cache.
Results sent to RAM
Factors affecting CPU performance
Processor Clock Speed
Amount of Cache Available
Number of cote processors
Describe clock speed
signal synchronising process by switching between 0 and 1 at a fixed rate measured in Hz
Higher clock speed means more instructions can be executed per second
describe cache memory
a high performance RAM,stores data waiting to be processed by CPU. Usually built into processor to minimise access time
what is L1 cache ?
cache that’s a part of the CPU. It is the smallest but the fastest to access (between 8 and 64 kb)
what is an L2/L3 cache ?
extra cache built in between CPU and RAM. they have a longer access time but a larger capacity
describe multi core
a greater number of cores so instructions can be executed simultaneously
advantages of underclocking
less power consumption also battery lasts longer
heat generation is lower so less damage risk
this means a fan can be removed making the machine work silently
advantages of overclocking
increased CPU performance so demanding applications work faster and smoother
dangers of overclocking?
increased power consumption and heat generation and therefore increased risk of catching fire or causing heat damage
this would mean warranty is void
ROM characteristics
data can’t be deleted or altered. non-volatile read only 1 or 2 mb used to boot up systems contains BIOS
what does BIOS stand for ?
basic input output system
what are BIOS?
Its a bootup program that checks computer’s functionality. It performs check using bootup loader and gives control to the OS.
characteristics of RAM
OS needs to be loaded into it for it to run stores working and opened programs can be accessed and changed at any time volatile usually 8GB
what does ROM and RAM stand for ?
read only memory.
random access memory
characteristics of virtual memory
part of the hard drive that is used as a RAM extension
memory is divided into physical units known as PAGING
used when RAM is full to keep wanted programs opened
data is stored temporarily and needs to be copied to RAM before it can be used again
what is PAGING
it’s when the memory is divided into physical units
what is DISK THRASHING
having to move data between hard disk and RAM slowing down your machine
is a sensor an input or output device ?
input
printer types ?
laser, thermal,plotter
2 pieces of primary memory ?
RAM and ROM
Primary memory ?
can be accessed directly by CPU
What are the other 2 factors affecting processor performance?
Width of the bus
What is the width of the bus and how does it affect processor speed?
The amount of data the processing unit can transmit at a time. The data is called words and it is an amount of bits that are addressed.
What are some common input devices?
BARCODE READER - bars and spaces represent characters in a code when they’re scanned.The laser light is either absorbed or reflected.
RFID - uses numbers to obtain details in a computer database
What does pipelining allow ?
Allows the processor to handle more than one instruction at a time but each in a different part of the fetch-d-execute cycle.
What does pipelining require ?
A RISC structure to allow different circuitry to handle the fetch-decode-execute cycle. Also requires a Harvard Architecture..
What is pipelining?
The next instruction execution process is started before the previous is fully finished.
What is a John Von Neumann Architecture?
A processor architecture where memory is used to store both programs and data together.This uses the fetch-decode-execute cycle and works therefore one instruction at a time.
Where is the John Von Neumann Architecture used?
Desktop Computers
Laptops
Workstations
High Performance Computers
What is the Harvard Architecture?
A processor in which there is a separate memory for data and programs/instructions.it utilizes the CU right in the middle of the structure.
Why can pipelining be used within a Harvard Architecture?
Since there is seperate buses and memory for data and instructions. This means that the CPU is capable of reading and fetching at the same time.
Why can’t we use pipelining with the Von Neumann Architecture?
Since there is only one bus so it isnt able to fetch instructions at the same time as data is sent. This si known as bottleneck.
How many cycles does it take for Von Neumann and Harvard Architecture to carry out instructions.
Von Neumann - 2 clock cycles
Harvard - 1 clock cycle
Where is Harvard Architecture used?
Embedded Systems
DSP (signal processing)
What is bottleneck in Von Neumann Architecture?
Delay of transmission of data through a microprocessor or TCP/IP network. The throughput of a computer system is limited due to there being only one bus.
