Internal Computer Hardware ( 2 ) Flashcards Preview

CS AQA SECT 6 > Internal Computer Hardware ( 2 ) > Flashcards

Flashcards in Internal Computer Hardware ( 2 ) Deck (23):
1

What is memory write?

Causes data on the data bus to be written into the addressed location

2

What is memory read?

Causes data from the addressed location to be placed on the data bus

3

What is interrupt request?

Indicates that a device is requesting access to the CPU

4

What is bus request?

Indicates that a device is requesting access to the CPU

5

What is bus grant?

Indicates that the CPU has granted access to the data bus.

6

what is clock?

Used to synchronise operations

7

What is reset?

Initialises all components.

8

What is the purpose of the data bus?

• Data bus carries the data both to and from memory, and to and from I/O controllers
• Provides a bi-directional path for moving data and instructions between system components.

9

What determines overall system performance?

• Width of the data bus.
A data bus of n length can therefore transmit any item of data that can be represented using 2^n combinations ( e.g. 8 wires, 2^8 representing 256 combinations ).

10

What happens if you have a larger width on the data bus?

• Width of the data bus determines overall system performance.
• The greater the width of the data bus, the more data can be transmitted in one pulse of the clock.

11

What is the purpose of the address bus?

• Address bus carries the address of the piece of memory or I/O device to be read from or written to
• Used to access anything that is stored in memory.

12

What directions does the address bus travel in?

Unidirectional, it only travels in one direction from CPU to memory.

13

What occurs when the processor wishes to read a word of data from memory?

Puts the address of the desired word on the address bus.

14

What does the width of the address bus determine?

• Maximum possible memory capacity of the system.
• Represents the amount of memory that is addressable.

15

What is the purpose of the control bus?

• Ensure that the correct data is travelling to the right place at the right time.

16

What is an I/O controller?

• A device which interfaces between an input or output device and the processor.

17

How does an I/O controller work?

• Each device has a separate controller which connects to the control bus
• I/O controllers receive input and output requests from the processor, and then send device specific control signals to the device they control.

18

What is the purpose of the I/O controller?

• I/O controllers receive input and output requests from the processor, and then send device specific control signals to the device they control.
• Manage the data flow to and from the device.

19

What does an I/O controller consist of?

Electronic circuit board consisting of three parts:
• Interface that allows connection of the controller to the system or I/O bus
• Set of data, command and status registerse
• Interface that enables connection of the controller tot he cable connecting the device to the computer

20

What is an interface?

Standardised form of connection defining such things such as signals, number of connecting pins/sockets and voltage levels that appear at the interface

21

What is a key feature of the I/O controller?

• Translate signals from the device into the format required by the processor.

22

Why is an I/O controller needed?

• There are many different devices and many different types of processor and it is the I/O controller that provides the flexibility to add new devices without having to redesign the processor.

23

Why is the I/O controller used to buffer data being sent between the processor and device?

• I/O devices respond relatively slowly compared to the speed at which a processor can work
• Used to buffer data being sent between the processor and device so that the processor does not have to wait for the individual device to respond.