1.1: Systems Architecture

Question 1

What is the difference between hardware and software?

Answer 1

Hardware is a physical component of a computer, software is a program that runs on a computer

Question 2

Draw a basic computer system model

Answer 2

Input with arrow to CPU
Memory and secondary storage with 2 way arrows to CPU
Output coming from CPU

Question 3

Name 4 input devices

Answer 3

Mouse and keyboard, microphone, camera, thermistor

Question 4

Name 4 output devices

Answer 4

Speaker, monitor screen, printer, actuator

Question 5

Name the 2 main functions of the CPU

Answer 5

To process data and information
To control the rest of the computer system

Question 6

Name 5 functions of the control unit (CU)

Answer 6

. It controls the execution of instructions in the correct sequence
. It decodes instructions
. It regulates and controls CPU timing using regular pulses
. It sends and receives control signals to and from other hardware pieces within the computer
. Controls data movement

Question 7

What is the function of the arithmetic logic unit?

Answer 7

It performs logic operations, shift operations and arithmetic operations

Question 8

What is the cache?

Answer 8

A small amount of fast RAM which provides fast access to frequently used instructions and data

Question 9

What does the clock do?

Answer 9

Sends out electrical pulses at regular intervals to synchronise the components of the computer.

Question 10

What is a register?

Answer 10

A small amount of high speed memory used to store small amounts of data that are needed during processing

Question 11

What is an address?

Answer 11

The location of a piece of information

Question 12

What does the program counter (PC) do?

Answer 12

Holds the memory address of the next instruction to be processed

Question 13

What does the memory address register (MAR) do?

Answer 13

Holds the address of where data is to be fetched from or stored into

Question 14

What does the memory data register (MDR) do?

Answer 14

Holds data or an instruction temporarily after it has been fetched from memory or about to be sent to memory

Question 15

What does the accumulator (ACC) do?

Answer 15

Temporarily holds the result of operations carried out by the ALU

Question 16

Describe the process of the fetch stage in the fetch-execute cycle

Answer 16

Program counter is checked for address of next instruction. The address is used by the MAR to fetch the instruction from the main memory and bring it back to the MDR. PC looks for next address.

Question 17

Describe the process of the decode stage in the fetch-execute cycle

Answer 17

Now the instruction is in the CPU, the CU decodes the instruction to see what has to be done

Question 18

Describe the process of the execute stage in the fetch-execute cycle

Answer 18

The instruction is carried out. What is done depends on the instruction, such as fetching data from the RAM and adding it to the accumulator or writing data in the accumulator into RAM

Question 19

What are the 3 main stages of the FE cycle?

Answer 19

Fetch, decode, execute

Question 20

What 3 main factors affect the CPU’s performance?

Answer 20

Clock speed, cache size, number of cores

Question 21

What does an increase in clock speed do to the CPU?

Answer 21

Increasing the clock speed increases the number of instructions processed/cycles per second

Question 22

What is clock speed measured in?

Answer 22

Hertz

Question 23

What is the average clock speed for a PC?

Answer 23

Between 2GHz and 4GHz

Question 24

What happens to CPU performance when cache size is increased?

Answer 24

The more data and instructions can be held in cache and made available quickly, increasing processor performance

Question 25

What is a core?

Answer 25

A complete copy of a CPU, each with its own registers, ALU, CU etc.

Question 26

What can the CPU do with multiple cores?

Answer 26

Run more than one fetch-execute cycle at once, thus operating faster than a single-core processor

Question 27

Why does doubling the amount of cores not double the overall speed (2 reasons)?

Answer 27

Cores need to communicate with each other which takes time, and many programs are not designed to run at maximum efficiency with multiple cores

Question 28

What is an embedded system?

Answer 28

A computer system with a dedicated function within a larger system

Question 29

Give 6 examples of embedded systems

Answer 29

Cars
Cameras
Medical equipment
Vending machines
Aircraft
Televisions
Ovens
Etc.

Question 30

Give 4 characteristics of an embedded system

Answer 30

Cannot be changed - program is held in ROM
Simple user interface, or none at all
Require little power - may run on batteries
Low cost per unit - cheap to design and build