Interal Hardware componets

What is a processor ?

Executes program instructions in order to run application

What is main memory ?

Uses RAM / ROM to store program instructions and frequently used data

What is a bus ?

Series of parallel wires that connect internal components of a computer system

What is width ?

The number of parallel wires in a bus and has direct elation to the number of bits that can be sent simultaneously

What is an address bus ?

Carries Address of memory location in 1 direction from processor to memory.

What happens when you increase the width of the address ?

It increases the range of the address that can be specified

What is addressable memory ?

Portions of memory hat can be accessed by its address - if not enough dresses some memory ca go unused

What is a data bus ?

Sends data and instructions to and from the diff ent components of the computer system - bidirectional

What happens when I increase the width of the data bus ?

It will increase the volume of data that can be transferred over the bus at any one time

What is a control bus ?

Carries the control signals that regulates the operations of the computer system - also carries the computer clock signal

What are I / O controllers ?

Pieces of hardware that control the communication of data between the processor and external hardware devices such as keyboards

What does I / O controllers manage ?

Data flow to and from the device freeing up the cpu allowing it to do other tasks

What is the stored program concept ?

Machine code instructions are fetched and executed serially by a processor that performs arithmetic and logical operations.

What is the von neuman architecture ?

Data and instructions are stored together in the same memory - general purpose

What is the Harvard architecture ?

Data and instructions are in separate memory locations - embedded systems / digital signal processing

What is the arithmetic logic unit ?

Performs the arithmetic and logical operations

What is the control unit ?

Controls / coordinates the activities of the components and each set is synchronised to the internal clock

What are registers ?

Small storage locations that stores regularly used data temporarily with a high read write speed

What is a general purpose register ?

Register that stores and type of data that is required during the execution of the instruction - RAM

What is a special purpose register ?

Stores specific information like the current instruction being held

What is a PC ?

Program Counter - Holds the memory address of the next instruction to be executed

What is a CIR ?

Current Instruction Register - holds the instruction that is being executed by the processor

What is the MAR ?

Memory Address Register - stores the memory address of the memory location that is to be read or written

What is the MBR ?

Memory Buffer Register - holds the content of a memory location that has been read or written

What is SR ?

Status Register - Contains bits that are either set or cleared which can be referenced individually.

What is the clock ?

Generates a timing signal which changes at a regular frequency

What happens in the fetch stage ?

• contents of PC is copied in to MAR
• contents of MAR is transferred in to main memory by the address bus
• instruction is sent from mai memory to the MBR by the data bus
• PC increments by one
• contents of MBR Is copied in to the CIR

What happens in the decode stage ?

• contents in the CIR is decoded by he control unit into opcode and operand

What happens in the execute stage ?

• any data that is required by the instruction and isn't present in the register is fetched from main memory
• the instruction is carried out
• results of any calculations is stored in main memory or a general purpose register

What happens between each stage of the fetch excite cycle ?

The contents and status of the registers are checked for any changes that might be an interrupt

What is an interrupt ?

A signal that is sent to the processor by another part requesting the attention of the processor

What happens when an interrupt occurs ?

Contents of the register is placed into the system stack 'saving volatile environment'
Then it loads the appropriate interrupt service routine
After it restores the volatile environment and resumes execution

How does the core affect the processor performance ?

Directly affect the performance by allowing each care to indecently perform the fetch execute cycle allowing more processing going on at once

How does the cache affect the processor performance ?

More cache the more frequently used data that can be stored and saves more time from getting it form main memory

How does the clock speed affect the processor performance ?

Higher frequency the more fetch execute cycles that can be performed in the same period of time

How does the word length affect the processor performance ?

Higher the word length the more bits that can be transferred

How does the address bus affect the processor performance ?

Increasing the amount of wires will increase the amount of addressable memory and the range of addresses that can be specified

How does the data bus affect the processor performance ?

Increasing the volume of data that can be transferred over the bus at one time will allow more data to be fetched for main memory in one cycle

What is the processor instruction set ?

Each processor has its own instruction set so may not be compatible / a group of instructions followed to carry out a task

What is opcode ?

The type of operations that are going to be used

What is operand ?

Piece of dat on which the operation is performed

What is addressing mode ?

One bit in the machine code which describes the data

What is immediate address ?

Value specified by operand is the be treated as an actual value

What is direct address ?

Value specified signifies a memory address

What is a logical shit ?

A process that shift all bits left or right to multiply or divide

What does AND do In a logical shift ?

Masks out certain bits of a number

What does OR do in a logical shift ?

Set bits to one without affecting the other bits

What does NOT do in a logical shift ?

Used to fined 2's compliment