Section 1 Flashcards
(141 cards)
What is a CPU?
It has a number of different components which enables it to carry out its task of executing instructions
What components are in the CPU?
Control Unit
Buses
Arithmetic Logic Unit (ALU)
Dedicated Registers
What does the control Unit do?
The CU controls and coordinates the activities of the CPU, directing the flow of data between the CPU and other devices
How does the Control Unit work?
It accepts the next instruction, decodes it into several sequential steps such as fetching addresses and data from memory, manages its execution and stores the resulting data back in memory or registers
What is a bus?
A bus is a set of parallel wires connecting two or more components of a computer.
What is the number of lines in a bus?
It typically consists of 8, 16, 32 or 64 lines
How do all the buses work?
When the CPU wishes to access a particular main memory location
1) It sends this address to memory on the address bus
2) The data in that location is then returned to the CPU on the data bus
3) Control signals are sent along the Control bus
What is a system bus?
The three bus, address, data and control bus are collectively known as the system bus.
What is a shared transmission medium?
Each bus is a shared transmission medium, so that only one device can transmit along a bus at any one time.
Which buses travel in both direction?
Data and control signals travel in both direction between the processor, memory and input output controllers
Which buses travel only one way
Addresses travel only one way along the address bus: the processor sends the address of an instruction, or of data to be stored or retrieved, to memory or to and input output controller
What are the three buses called?
1) Control bus
2) Data bus
3) Address bus
What is the purpose of a Control bus?
The purpose of the Control bus is to transmit command, timing and specific status information between system components
The Control bus is a _______ bus
Bi-directional
What does the Control line do?
Control lines must be provided to ensure that access to and use of the data and address buses by the different components of the system does not lead to conflict
Control lines include:
Bus request Bus grant Memory write Memory read Interrupt request Clock
What is bus request?
Indicates that a device is requesting the use of data bus
What is bus grant?
Indicates that the CPU has granted access to the data bus
What is memory write?
Caused data on the data bus to be written into the addressed location
What is memory read?
Causes data from the addressed location to be placed on the data bus
What Is interrupt request
Indicates that a device is requesting access to the CPU
What is clock (control lines)
Used to synchronise operations
What is the purpose of a data bus?
It’s provides a bi-directional path for moving data and instructions between system components. Typically has 8, 16, 32 or 64 separate lines
Memory is divided up internally into units called….
Words