Paper 1 Computer Science Revision

Question 1

Name one input device and one output device that might be part of Bertie Butler. For each
device give a reason for it being built into the virtual assistant.

Answer 1

Input Devices:
- Microphone to allow the device to hear spoken requests.
- Buttons to turn the device off or on / To mute
device/ to put device in privacy mode
Output Devices:
-Speaker to play the device’s responses
LEDs to indicate the device is on/listening
Screen to show visual information

Question 2

Define the term ‘embedded operating system’.

Answer 2

System software/software used to manage the device which is built into the device itself, stored in the device’s ROM/cannot be changed specific to the hardware/purpose

Question 3

Define the term ‘multicore processor’

Answer 3

more than one processing unit in a (single) processor which can independently process instructions at the same time.

Question 4

The code uses direct addressing. Describe one other mode of addressing.

Answer 4

• Immediate addressing operand is the value to be used.
  -Indirect Addressing operand is the memory location holding a value representing the memory location to be used.
  -Indexed Addressing Operand is added to contents of Index Register to get memory location
  of value needed.

Question 5

Giving an example other than DVDs, describe what is meant by the term ‘optical media’.

Answer 5

One from read/written to, using a laser read/written onto a reflective surface data is stored using pits and lands
Example = Blu-Ray/CD

Question 6

Give one advantage of films being distributed using optical media

Answer 6

Cheap to produce/buy Capacity big enough to hold film
Robust enough to be used over long
periods/ moved around
Portable
Does not need an internet connection

Question 7

State the purpose of a device driver.

Answer 7

A program that enables communication between an operating system and a (hardware) device.

Question 8

Explain the advantages and disadvantages of owning films that are streamed or downloaded
on demand rather than owning a physical copy.

Answer 8

Advantages
Can access film (and indeed entire library) from anywhere with an internet connection
No physical storage needed No risk of films being stolen/damaged/lost
Optical/disk player hardware not required to play film
Disadvantage
Reliant on having an (fast enough) internet connection.
Need enough storage for download − Reliant on servers of the company
providing the connection.
People like having a physical copy
If the company providing the stream goes out of business, copy is lost.

Question 9

State the name of a data structure that could be used to store a single site’s details.

Answer 9

tuple / record / list

Question 10

Define the term ‘utility’.

Answer 10

A program with one purpose/piece of system software used for the upkeep/maintenance of the system

Question 11

State how an application differs from a utility.

Answer 11

Application performs tasks for the user (rather than computer). Performs generic (rather than specific)
tasks

Question 12

Explain what is meant by Extreme Programming and why it is a suitable approach in this
case.

Answer 12

Extreme programming is a software development methodology 
Focus is on good quality code 
It is an agile paradigm 
it is designed to allow development to
respond to changing user
requirements.
Involves paired programing Program is regularly reviewed/iterative
process. 
Suited to this scenario
Types of virus/threat is continually
changing/updating
− In order to detect virus effectively there
needs to be an emphasis on code
quality.

Question 13

Explain why the programmers of anti-virus software may make use of virtual machines when
developing the updates.

Answer 13

Allows them to run the update on a
number of different systems/OSs without needing multiple physical
machines. They can put viruses on the VM to test
if the update can catch them
- …but protect the physical machine
from the virus/the VM can quickly be
reset to its original state.

Question 14

Explain why a First Come First Served scheduling algorithm would not be suitable in this
situation.

Answer 14

FCFS means jobs are completed in the
order they arrive ineffective in catching viruses/the virus
may run first the virus checker may never run/take
a long time to start running the virus checker may be continuously running this will temporarily stall the system/
all other processes have to wait.

Question 15

Describe what the effect would be of a computer having its BIOS overwritten.

Answer 15

The computer would not be able to boot/load the OS Or set up its initial configuration/hardware checks Making the computer unusable

Question 16

Explain what is meant by referential integrity, giving an example which refers to the database
described above.

Answer 16

Ensuring that changes are consistent 3 across a database if a record is removed all references to
it are removed A foreign key value must have a corresponding Primary key value in another table. In this case, a user being removed will result in their reviews being removed/ a restaurant being removed will result in
its reviews being removed.

Question 17

State what is meant by the term ‘server’.

Answer 17

A device which provides a central point of control/access

Question 18

Explain why it is important that the review score that the user entered is also checked server-side.

Answer 18

Client side processing can be modified And can sometimes be disabled on the browser To prevent malicious code (such as an
SQL injection/XSS) To prevent a non validated review (one with a score of over 5) being sent to
the server

Question 19

Describe what is meant by the term ‘Atomic’ in the context of ACID transactions. You should
refer to the example of a review being added.

Answer 19

A transaction/review can only fully complete or not complete / cannot partially complete In this case, it should not be possible
for the review to be added without the (average) rating being updated.

Question 20

State what the letters CID refer to in ACID

Answer 20

Consistency - the total value of funds in both the accounts is the same at the start and end of each transaction.
Isolation - property of a database where no data should affect the other one and may occur concurrently
Durability - ensures that changes made to the database (transactions) that are successfully committed will survive permanently

Question 21

Give an advantage and disadvantage of changing character sets from ASCII to Unicode UTF-32.

Answer 21

Advantage
More characters can be represented may include foreign alphabets may include emojis
Disadvantage
Reviews take up more storage (4 times their previous storage size).

Question 22

Discuss the positive and negative impacts computers are having on the environment.

Answer 22

The materials and fuel used in producing and transport computers has an environmental impact digital devices have short life spans and are quickly disposed of they often end up in landfill or are sent to less economically developed countries to be dismantled due to the value of some of the materials inside them, devices made up of toxic materials like mercury these can harm people disposing of the waste and damage/pollute the area in which they are buried/burned
People have many digital devices, these all need charging this means there is an increase in demand for electricity, means an increase in fossil fuels being burned
Computers are being used to automate the use of things like central heating, this can reduce electricity consumption
Computers have encouraged a paperless approach both in the workplace and in terms of companies sending bills to homes this has potential to reduce deforestation
Developments in digital storage reduced the need for physical media to be produced reducing plastic use
Allowed people to work at home and communicate from afar this means they dont have to travel, reducing pollution
Can analyse data which can be used in improving efficiency - data mining

Question 23

The web development company is looking to recruit a programmer to build websites.
Discuss the technologies the programmer would need to know and use and the importance of
each one.

Answer 23

HTML they understand how to write web pages
CSS they understand how to define the formatting of websites
JavaScript they understand how to write client side code allowing them to add interactivity to the website
Understanding of HTML/CSS and JavaScript is essential for the role. Without knowing
HTML it is impossible to handcode webpages.
Whilst WYSIWYG tools exist these often produce inefficient code and at any rate it will
be necessary at some point to hand tweak the code. (As the role is ‘programmer’ it is
reasonable to expect that the site will be coded.)
CSS is nearly as essential. Whilst HTML can be used for a lot of the formatting, this is
considered bad practice. CSS will allow them to make consistent looking sites.
JavaScript is also essential as most websites have an interactive element (e.g.
validation of forms)
Knowledge of Server-side processing/PHP/ASP etc…
…allowing them to write dynamic websites.
This is important if the company wants to produce websites with content that changes
Databases…
…allowing them to allow websites to store and retrieve data.
Some knowledge of databases will be useful if writing dynamic sites. This will largely
be focussed around SQL.
Photo editing…
…allowing them to prepare images for the website.
This is less essential as in many cases the assets will be pre-prepared. A basic knowledge, Knowledge of software engineering practices…
…allowing them to work as part of a team when building the website.
The importance of this will depend on the size of the team working on the site.
May mention more advanced technologies e.g. AJAX, SOAP, JSON etc.

Question 24

State two features of the Von Neumann architecture.

Answer 24

(Single) Control Unit
(Single) Arithmetic Logic Unit
(Special) registers within CPU
Instructions and Data stored in same area of memory Instructions and Data stored in same format
A single set of buses / same bus for instructions &
data (to connect CPU to Memory and I/O)

Question 25

Describe one feature, not part of the standard Von Neumann Architecture, which
contemporary CPUs may have in order to improve performance.

Answer 25

Two separate areas of memory one for instructions & one for data./instructions and data can be accessed concurrently.
Different (sets of) buses one for instructions & one for data./ instructions and
data can be accessed concurrently.
Pipelining whilst an instruction is being executed the next can be decoded and the subsequent one fetched.
Use of Cache A small amount of high performance memory is (next to the CPU) / which stores frequently used
data/instructions
Virtual cores/Hyper-threadingTM Treating a physical core as two virtual cores.
Multiple Cores Each core acts as a separate processing unit.
Onboard Graphics Built in circuitry for graphics processing.

Question 26

List three functions, other than memory management, of an operating system.

Answer 26

Provide a (user) interface
Manage hardware/peripherals
Manage CPU usage / handles interrupts
Provide security
Provide platform to run other software
Provide utilities for system maintenance

Question 27

State the name of the type of memory management used in Fig. 2.

Answer 27

Paging

Question 28

Describe how the operating system would use virtual memory to load program C.

Answer 28

Operating system uses area of secondary storage
as virtual memory.
Move unused pages/parts (of program A and/or
B) into virtual memory
Load program C into (physical) memory.

Question 29

Explain what happens when a search engine indexes the page. You do not need to
discuss ranking.

Answer 29

A program called a spider/crawler/bot
Traverses the web / following the links.
It takes each word in the document
It adds an entry for the page (under the word) in
the index alongside the word’s position on the page.

Question 30

Explain why using a RISC processor rather than a CISC processor is likely to result in
increased battery life.

Answer 30

RISC has a smaller instruction set (than CISC)
Requires fewer transistors / less complex circuitry
Means less power is required.

Question 31

Describe one format or method the airport could use to provide the data to the airlines so
they can use it in their own applications.

Answer 31

CSV/Comma Separated Value (file) A (text) file/format with values separated by
commas (or some other delimiter)
XML/eXstensible Markup Language A markup language that uses tags to denote data.
SQL/Structured Query Language A language for creating/querying databases

Question 32

State the name of an input device and describe how it could be used by a user with very
limited mobility in their hands and arms to send a signal to the computer.

Answer 32

Foot mouse/pedal press key/click button to send signal.
Camera/eye tracker
Move/blink to send signal
Microphone Make sound to send signal
Puff/suck switch blow/suck to send signal.

Question 33

Explain the benefits to the users of the software being open source.

Answer 33

Free of cost
Right to inspect/amend/recompile source code
Can tailor the program to their specific needs
Code open for bugs to be spotted and fixed.

Question 34

Explain why the self-driving system will use a real-time operating system.

Answer 34

Needs to be able to respond instantly to
changes such as someone stepping in front of car (or
other sensible example)
RTOS offers a guaranteed response time.
A non RTOS might be busy dealing with other
tasks and not respond until it is too late.

Question 35

Give one advantage and one disadvantage to the customers of the taxi using self-driving
cars rather than drivers.

Answer 35

Advantages of an automated driver are it is potentially:
- safer than a human driver (due to quicker reaction
speeds etc.).
- cheaper as no wage to cover.
- less likely to make mistakes with route.
Disadvantages of an automated driver are it is
potentially:
- May not be able to understand natural speech.
- May be limited in terms of the roads on which it
can operate.
- Vulnerable to hacking.
- Only as good as the program running it – a bug in
the code could cause catastrophic accidents.
- May prioritise safety of pedestrians over that of
the passenger. (e.g. may take actions that may
put the passenger at risk to save the lives of
numerous people outside the car.)
- No discussion possible with the driver / no
“human presence” to reassure nervous
customers.

Question 36

Meant by the term ASCII

Answer 36

American Standard Code for Information Interchange
A character set
Maps values to characters
uses 7 bits/8 bits per character

Question 37

Give one use the firm might have for GPUs.

Answer 37

To render models of proposed buildings.
Run CAD software.
Run modelling calculations.
Any example sensible to scenario

Question 38

Describe what is meant by the term ‘RAM’.

Answer 38

Random Access Memory
A form of primary memory
Used to hold data and/or programs in use
Volatile/Loses its contents when power is
lost.

Question 39

State one characteristic a high performance CPU might have.

Answer 39

Multiple Cores
High/Fast Clock Speed
Ability to use pipelining
Large Cache

Question 40

State the name of and describe two methods that the operating system can use to divide
the contents of RAM.

Answer 40

Paging Memory is divided into fixed/physical units

Segmentation Memory is divided logically/variable size according to its contents.

Question 41

Explain, giving an example, why the firm’s computers use operating systems capable of
multi-tasking.

Answer 41

Multitasking allows the user to run more than
one program at the same time.
E.g. running CAD software whilst checking
emails.

Question 42

Give one advantage and one disadvantage to the architects’ firm of a client-server set
up rather than a peer to peer setup.

Answer 42

Advantage:
Centrally administered in one location.
One location to back up. 
Disadvantage:
Central point of failure. 
Can be expensive to maintain/set up
(e.g. cabling costs, specialist staff.)

Question 43

The LAN is connected to the Internet via a firewall. Describe the term ‘firewall’

Answer 43

A hardware device/piece of software that
monitors (and filters/blocks) traffic/packets going
to and from a network.

Question 44

State why the architects’ firm would use a firewall.

Answer 44

Prevent unauthorised access to a network.
To restrict applications that are used internally that
have internet access.
To restrict websites that can be accessed from within
the company.
To protect the company’s data/intellectual property.

Question 45

Describe what is meant by the term ‘linked list’.

Answer 45

A dynamic/data structure
Each node/item consists of data and pointer
Pointer gives location of next node.

Question 46

Describe what is meant by the term ‘primary key’, giving an example from the table above.

Answer 46

A field which has a unique value for every record/A
unique identifier.
userID

Question 47

Describe what is meant by the term ‘hash’

Answer 47

A result generated by applying an algorithm/numeric

process to a value.

Question 48

Describe one advantage to storing the password as a hash.

Answer 48

Hash functions are one way/can’t be reverse
If someone gains access to the database they cannot
access user’s password.

Question 49

Explain the difference between a HTML id attribute and a HTML class attribute.

Answer 49

Only one element can have a given id/id is unique.
Class can be used assigned to multiple
elements/used multiple times.

Question 50

Give one disadvantage of this code being run client side rather than server side.

Answer 50

• Won’t work if JavaScript is disabled.
• Shows incorrect message if user’s computer’s
  clock is wrong/in different time zone.
• (Source) code is visible allowing it to be
  copied/modified.

Question 51

Describe the Rapid Application Development process.

Answer 51

• Prototype is created
• (Evaluated and) feedback used to inform next
  iteration
• Any changes are made
• Process repeated until prototype becomes final product.

Question 52

Give two advantages to the software team of using a library.

Answer 52

• Function traverses every letter of answer
• Function traverses every randomLetters
• Correctly checks each letter of answer against
  each of randomLetters
• Returns 0 if answer contains a letter that doesn’t
  occur in randomLetters
• Returns 0 if letter occurs more times in answer
  than randomLetters
• Returns answer length for a valid word.