1.

1 Systems architecture
Objectives

1. Understand that a general-purpose system is used to execute programs.

2. Define the terms 'hardware' and 'software'
3. Define a computer system
4. Describe what a computer system does

1. Fill out the gaps using these words: execute(s) | instruction(s) | comprise(s) |
operate(s) :
A computer system comprises of hardware and software (programs). The
hardware executes programs. Programs are made up of instructions which
operates on data.

2. State what is meant by computer software.

Programming code which makes up the computer.

3. State what is meant by computer hardware.

Physical parts which make up a computer.

4. State what is meant by a computer system.

Hardware and software combined make a computer,

5. Other than those on this page, give one other example of hardware.

CPU.

6. Other than those on this page, give one other example of software.

Windows.

7. State possible inputs, processes, storage and output for a calculator.

1+1 = 2.
1.1.1 Architecture of the CPU

Objective

1. Name the main sections inside a CPU

1. Name some of the output devices mentioned in the video.

Monitor, mouse, keyboard…

2. Name three parts of the CPU.

ALU, CU, registers,

The CPU

Objective

1. Know the purpose of the CPU.

1. Someone gives you the lyrics for "The Hokey Cokey". Describe how getting
them and then performing the actions to it can be seen as an example of
'fetching, decoding and executing' instructions.

Fetch the lyrics, find out what you want to do, action on your decision.

1. Define the purpose of the CPU.

To fetch, decode and execute instructions,

2. Find an example of a system and label it with possible inputs, processes and
outputs. E.g. consider the inputs, processes and outputs for a processor
found in a SATNAV system.
The fetch, decode, execute cycle

Objectives

1. Know the name of each stage in a processor cycle

2. Understand how programs run using the 'fetch-decode' cycle.

1. State the names of the three parts of each CPU cycle.

Fetch, decode and execute,

2. State where a CPU fetches instructions from.

MDR.

3. Name the part of the processor that works out the meaning of each
instruction.

CU.

4. Describe how the CPU is kept synchronised.

CPU clock – clock speed.

 5. Describe the relationship between the processor speed and system
performance.

Higher processor speed = higher system performance.

Control unit, registers, ALU, cache

Objectives

1. Know the role and purpose of the Control Unit

2. Know the role and purpose of the ALU (Arithmetic Logic Unit)
3. Know the role and purpose of the Registers
4. Know the role and purpose of the CPU Cache Memory
5. Know the role and purpose of the busses (AQA only)

1. State the purpose of a register

Manipulates data.

2. Describe the role of the control unit

Sends signals to control how data moves around the CPU.

3. Describe the role of the ALU

Performs calculations and logical decisions,

Registers

Objective

1. Know the purpose of each register and what it stores (data or address)

1. Draw a diagram from memory to show the registers inside a CPU.

 2. State which of these stores a single address: MAR, MDR, CPU Cache,
Program Counter, RAM.

MAR.

3. State which of these stores frequently used instructions: MAR, MDR, CPU
Cache, Program Counter, RAM

Cache.

4. State which of these is a register: MAR, MDR, CPU Cache, Program Counter,
RAM

MAR, MDR.

5. Name and state the purpose of one other register that is not mentioned
above.

RAM – holds volatile data,

1.1.2 CPU Characteristics

Objectives

1. Name three characteristics of a CPU that impacts on its performance.

 2. Be aware of other factors that can impact on the overall performance of a
computer.

1. Name three characteristics of CPUs that affect their performance (HINT: think
three 'c's)

Clock speed, number of cores, amount of cache,

Clock speed

Objectives

1. Understand what is meant by 'clock speed'

2. Explain the effects of changing 'clock speed' on system performance.

1. Describe what a processor with a clock speed of 4.2Ghz means.

More quicker processing.

2. Describe what is meant by the frequency of a processor.

How much data it can handle in one go.

3. Computer A has a 2.8Ghz processor. Computer B has a 1.2Ghz processor.

Explain why Computer A will usually run faster than computer B.

Higher clock speed.

4. Explain the likely impact of a computer that has had its processor changed for
one that has a higher clock speed.

Faster.

Cache memory size

 Objectives

1. Understand what is meant by 'CPU cache'

2. Explain the effects of selecting a CPU with a different amount of 'CPU
cache' on system performance.

1. State the purpose of cache memory.

Make computer more fast.

2. Describe how cache memory works.

Holds frequently used instructions.

3. Describe the effect on system performance of upgrading the CPU to one that
is identical other than having more cache memory.

Clock speed.

4. State which level of cache a processor would use to store the most frequently
used data in.

CPU.

Number of cores

Objectives

1. Understand what is meant by a CPU core

2. Understand what is meant by 'number of cores'
3. Explain the effects of selecting a CPU with a different number of 'CPU
cores' on system performance.

1. State what is meant by a quad core processor.

4 CPU’s.
 2. State what would broadly be the dual core equivalent of a 2.4Ghz single core
processor.

4.8Ghz.

3. Here are two CPUs.

(a) 3.2Ghz, single core
(b) 2.4Ghz quad core

Assuming everything else is equal, explain which processor you would buy.

B, as 4 cores make 9.6Ghz.

Embedded systems

Objectives

1. State what embedded systems are.

2. Give the purpose of embedded systems.
3. Give typical characteristics of embedded systems (OCR only).
4. Explain how embedded systems differ from non-embedded (general-
purpose) systems (AQA only)

1. State what is meant by an embedded system.

Dedicated function within a larger mechanical system.

2. Explain one benefit of using an embedded system instead of a general

purpose system to control traffic lights.

Low power consumption – doesn’t need to carry a lot of functions.

3. A car manufacturer is considering whether to use an embedded system, or

general purpose system to control a construction robot. Discuss which system
could be used.

Embedded system – does not need to carry many functions.

 4. Explain why an embedded system may be best suited for being put into a car
management system.

Low power consumption, small size – we don’t really use car systems that often
unless we want to listen to a radio.

Examples of embedded systems

Objective

1. Be familiar with a range of embedded systems.

1. List three examples of embedded and non-embedded systems. Try to include

examples that have not already been mentioned.

ATM, washing machine, coffee machine. Phone, console, computer.

2. Explain whether a 'smartphone' is a general purpose computer or an

embedded system.

General purpose – performs many functions.

3. Explain whether the system used to fly a Boeing 737 is a 'general purpose
system' or an 'embedded system.

Embedded system – doesn’t need to access the internet, most amount of

communication would be to an airport.

4. Explain whether a 'smart meter' that connects to the internet using WiFi to
record energy usage is an example of an 'embedded system' or a 'general
purpose system'.

Embedded system – still cannot perform many functions such as allowing the user to
access YouTube or Edge,