1.1: SYSTEMS ARCHITECTURE

Question 1

What is the purpose of the CPU?

Answer 1

To process data and instructions stored in memory by repeatedly carrying out the fetch-decode-execute cycle.

Question 2

Explain the fetch-decode-execute cycle?

Answer 2

-an instruction is fetched from memory, decoded by the control unit and executed, and the cycle repeats

Question 3

Functions of the control unit: MAIN POINT and additional ones (4 in total)

Answer 3

• issues control signals that control hardware
• provides timing signals
• fetches, decodes and executes instructions
• moves data around the system

Question 4

Functions of the Arithmetic Logic Unit: (3)

Answer 4

• performs arithmetic and logical calculations/ operations.
• acts as a gateway between primary memory and secondary storage. Data transferred between them passes through the ALU.
• bit shifts

Question 5

What are registers and what is their function? (2)

Answer 5

• small amounts of high-speed memory contained within the CPU.
• used by processor to store small amounts of data that are needed during processing

Question 6

What is the purpose and REASON that cache is important within the CPU? (what does it do, and how does that affect the CPU) (2)

Answer 6

• hold data and instructions that the processor is likely to reuse
• allows for faster processing as the processor does not have to wait for the data and instructions to be fetched from RAM.

Question 7

What is the purpose of a clock?

Answer 7

used to coordinate all of the computer’s component

Question 8

How does the clock complete its function?

Answer 8

-sends out a regular electrical pulse which synchronises all the components.

Question 9

What is the correlation between the clock and clock speed?

Answer 9

The frequency of the pulses is known as the clock speed.

Question 10

What is a bus and what is its function? (2)

Answer 10

• high-speed internal connection.

- used to send control signals and data between the processor and other components.

Question 11

program counter:

Answer 11

stores the address of the next instructions to be run (fetched from primary memory), and increments by 1 for every time an instruction is run

Question 12

memory address register (MAR):

Answer 12

stores the address where the next data will be fetched from

Question 13

memory data register (MDR):

Answer 13

stores the data that has just been fetched

Question 14

current instruction register (CIR):

Answer 14

holds the instruction that is currently being decoded and executed

Question 15

accumulator (ACC):

Answer 15

temporarily stores results by the operations carried out by the ALU

Question 16

Function of the Address bus:

Answer 16

-carries memory addresses from the processor to other components (such as primary memory and input/output devices)

Question 17

Function of the Data bus:

Answer 17

carries the actual data between the processor and other components.

Question 18

Function of the Control bus:

Answer 18

carries control signals from the processor to other components. The control bus also carries the clock’s pulses.

Question 19

EQ: Identify 2 input devices and one output device that may be connected to the CPU.

Answer 19

Input: keyboard, mouse, scanner, digital camera, microphone, webcam

Output: monitor, printer, speaker

Question 20

3 factors that affect CPU performance:

Answer 20

clock speed

• cache size
• number of cores

Question 21

what is clock speed?

Answer 21

-number of fetch-execute cycles per second.

Question 22

Why is cache memory more efficient than RAM?

Answer 22

• cache memory operates much faster than memory, as data is transferred in and out of cache memory more quickly.
• therefore it makes the CPU more efficient as less time is spent waiting for data to be transferred.

Question 23

what is clock speed measured in and how does it correlate to the number of instructions?

Answer 23

-clock speed is measured in hertz. The higher the frequency, the more instructions can be performed in any given moment of time.

Question 24

How will the CPU optimise its use of cache? and for what reason?

Answer 24

• use the fastest cache before using the next level or using RAM.
• in order to improve the performance speed

Question 25

What is a core capable of doing?

Answer 25

-each core is capable of fetching, decoding and executing its own instructions.

Question 26

What is the correlation between # of cores and CPU performance?

Answer 26

-the more cores a CPU has, the greater the number of instructions it can process in a given space of time.

Question 27

What is a possible problem that can be encountered w/ cores?

Answer 27

-the processor may not be able to perform multiple operations simultaneously if the software it is running is not designed for multi-core processors

Question 28

What is an embedded system?

Answer 28

a small computer that forms part of a larger system, device or machine

Question 29

Does an embedded system require a full operating system? and why?

Answer 29

-no since they perform limited and very specific tasks

Question 30

Why must embedded systems be reliable? Explain your answer. (2)

Answer 30

• they cannot be modified once manufactured

- the program that controls them is held in ROM

Question 31

What is the purpose of an embedded system?

Answer 31

to control the device and to allow a user to interact with it.

Question 32

Give some examples of embedded systems:

Answer 32

• Traffic lights
• Sound system
• Tumble dryer
• Electronic games
• Digital watches
• Washing machine
• Dish washer

Question 33

why do embedded system usually have slower clock speed?

Answer 33

-they don’t need to do a lot of processing since they have simple instructions compared to a desktop PC

Question 34

What is an advantage of using a microcontroller?

Answer 34

• cheaper to manufacture

- fewer components that could go wrong which makes them more reliable

Question 35

What assumption can you make from the fact that embedded systems often use less power than computer systems? and give an example of how this could be applied to real life.

Answer 35

-they are appropriate for use in small devices in which battery life is a consideration, for example, a smart watch

Question 36

Characteristics if an embedded system: (3)

Answer 36

• usually have a slower clock speed than desktop computers
• often use microcontrollers- which contain the CPU, RAM & ROM on one chip
• often use less power than computer systems