Q,5-7

JUNE PAPER 2009 SCENARIO 2

Scenario 2

Questions 5 to 7

Karpartco is a manufacturing company which has eight factories who make parts for the motor industry. They often need to develop new components and are sometimes asked

to make one-off items.

SCENARIO 2 Q5-7

5 (a) 3D inkjet printers can be used to produce prototype plastic working models as part of

CAD/CAM.(i) Describe how these models are produced by the

printer.[2]Any two points from:

• thin layer of powder sprayed from ink jet spray head

• machine repeats process building up layer after layer to form object

• it uses slicing (tomographic) technology

• places a binder/glue during the layering process

• can use plaster or ceramic in powder form

5A-I Q & A

(ii) Explain why it is useful to produce these prototype models.[2]

Any two points from:

• can handle/see components (before expensive tooling up)

• less expensive than making a model by conventional methods

• can test model (before expensive tooling up)

5A-II Q & A

(b) Name two other output devices used in CAD and explain why they are used.[4]

One mark for device + one mark for reason:• graph plotter

• produce large scale drawings on paper

• very accurate drawings on paper to any scale

• large screen• to allow development of new designs/products

• allows enlargement of components

• allows use of light pens (etc.)

• second monitor

• to show commands

5B Q & A

They frequently use video conferencing to keep Karpartco factories and suppliers in contact with each

other.6 (a) Describe the advantages to the company of using

video conferencing.[2]Any two points from:

• computer files can be updated in real time

• can be set up at short notice to overcome crises

• regular meetings become viable

• initial hardware costs are offset by savings in travel costs

• safety aspects – no risk of kidnapping/terrorism

• no travelling time required away from office hence more productive

6A Q & A

(b) The use of video conferencing has increased rapidly in the last few years. Describe the recent developments that have

led to this increase.[5]Any five points from:

• increase in terrorist attacks has driven the need for video conferencing

• faster communication/broadband connections

• wider availability of high speed links

• companies have tended to become global

• faster processors in computers now allow for jerk-free images

• multi-screen technology

• general improvements in technology has lowered costs/improved image quality

6B Q & A

Karpartco uses LANs within each of its factories. Each factory is connected to the other

seven. Karpartco factories using a WAN.7 Describe how the following components are used

in Karpartco’s networking system:(i) hubs[2]

• used to connect computers to server/computer

• not very efficient network device

• sends data to all linked devices

• may amplify received signal

• works at MAC level

Q 7I Q&A

(ii) routers [2]

• gateway device

• links LANs to make a WAN

• includes a firewall

• directs packets according to their IP address

• stores list of connected devices

• redirects packets to correct switch/hub

• translates protocols (between networks)

7II Q&A

(iii) switches.[2]

• an advancement on a hub

• directs the data stream only to the addressed device

• prevents congestion on segment of network

• uses a list of device addresses

• redirects ‘ack’ packet directly to sending computer

• works at MAC level

7III Q&A

(iv) telnet.[2]

• is a protocol (internet)

• used to gain access to another users computer/remote access to

• server

• used to transfer/access data

• requires a password login id

• lacks security

• uses TCP/IP protocol (as a lower level)

7IV Q&A

Question 5

A question about output devices required in the scenario.

(a)(i) A specific device that few knew about. By far, the worst answered question in the paper. Of all the

papers seen, no candidate had any real idea or experience of 3D printers. Most candidates gained no

marks for this question. Candidates should be prepared to answer questions about specific pieces of

hardware or software which are listed in the syllabus.

EXAMINERS REPORT Q,5

(ii) Too many responses of the ‘better, cheaper, quicker’ variety without any expansion. Nearly all the

marks given here related to testing.

(b) This should have been much easier than it proved to be, but again some candidates failed to expand

using the scenario. Some candidates gave answers that were not output devices.

Q,5 CONTINUED

Question 6

This used video conferencing as the scenario. Candidates often seemed unaware of how a business system

would work and gave responses based on webcams. Big international companies are concerned about the

safety of their staff and the costs of travelling to meetings and will use dedicated video conferencing suites.

A very high bandwidth is required at this level of video conferencing. Using a laptop webcam may be

suitable for a salesperson on the road but would not being used in this context.

EXAMINERS REPORT Q6

(a) Although candidates were able to give standard IGCSE level answers to the question very few

candidates related their answers to the given scenario. Consequently, most candidates achieved very

few, if any, marks for this question.

(b) This section required a discussion of the advances in technology that have influenced the growth in

video conferencing. This part of the question was better answered, most candidates explained that

developments in technology had led to better quality and that globalisation had increased the need for

communication. The quality of the responses differed but most candidates got some marks.

Q6 CONTINUED

Question 7

This question was about the basic elements which make up a computer network. Overall this was a poorly

answered question; few candidates achieved marks across all four parts of the question. There seemed to

be considerable confusion between the different devices and little appreciation of what telnet was. Many

thought it to be a method of joining telephones into a network.

(i) Hubs – few candidates gained more than one mark was gained for this question – usually for the

connection of all the computers.

EXAMINERS REPORT Q7

(ii) Routers – few candidates achieved marks here. Those who did mentioned the LAN joining the

WAN or connecting through to the internet. Many candidates relied or their knowledge of home

cable routers.

(iii) Switches – most candidates produced very confused answers with little correct knowledge

demonstrated.

(iv) Telnet – with the exception of perhaps 1% or 2% of the candidates, nobody showed any knowledge

at all regarding telnet, and the majority assumed it was the use of the telephone system to join to

the internet.

Q7 CONTINUED

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SOURCES