As Computing Mark Scheme

Level Mark Scheme for the May/June 2009 question paper for the guidance of teachers , maximum raw mark. This mark scheme is published as an aid to teachers and candidates, to indicate the requirements of the examination. It shows the basis on which Examiners were instructed to award marks.
It does not indicate the details of the discussions that took place at an Examiners’ meeting before marking began, which would have considered the acceptability of alternative answers. Mark schemes must be read in conjunction with the question papers and the report on the examination.
CIE will not enter into discussions or correspondence in connection with these mark schemes. CIE is publishing the mark schemes for the May/June 2009 question papers for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level syllabuses and some Ordinary Level syllabuses.

 Mark Scheme
Teachers’ version GCE A/AS LEVEL – May/June 2009 Syllabus

To allow the user to give the computer data/change data into computer understandable form
To allow the computer to give information/communicate with the computer/to change information from computer into human understandable form

To keep data while the computer is not using it (1 per dotty) [3] (b)

Black and white laser -e. g.
Use in office to produce letters
Produces high quality/speedy so does not develop large queue on a LAN
Colour laser -e. g.

To produce reports for a meeting

High quality outputs/can produce large quantity quickly
Dot Matrix – e. g.

Print receipts at checkout/tickets on railway

Produces more than one copy at a time, one for customer + one for shop
Inkjet -e. g.

Doing homework at home

Relatively cheap and slowness does not matter
Plotter -e. g.

Produce architect’s plans

Precision drawing tool
Braille printer
Producing documents/books for blind people
Outputs physical/3D form of data (3 per type, max 3 types, max 9)

Advantage
Processed/Searched more easily/quickly/Estimate of file size is easier -e. g.
When a customer wants to know the availability of an item the record can be found quickly/makes selection of storage easier
Disadvantage
The size of fields must be determined before use so space is often wasted/not sufficient -e. g.
The “description” field may not be large enough for a particular item. 1 per -, max 4) [4] 3

Working from home
Fewer journeys/more free time/less supervision…
Different types of jobs/jobs lost/job opportunities arising
Production line/manual jobs being lost/replaced by more technical jobs
Work done can be more visible to managers
All work/times working can be seen/leading to rewards where appropriate/sanctions when poor effort
Safety of workers is improved
Computers/robots do dangerous tasks/can be used to accurately monitor dangerous processes
Work time can be less rigid
Work can be fitted in round other commitments/leads to simpler ways of job sharing
The 24 hour job/office/commitment/world workforce
Workers may always be contactable/throughout the world/communications.

 Mark points

Begins with 5 (as first output)
Loop with working condition
Counter correctly incremented 5
Options appear on screen from which to select
Selection may lead to submenus
Menus arranged in a tree structure (from single root to many branches)

Use: In a passive information system e. g. Tourist guide at a train station. (1 for use, + 2 other -, max 3)

Follows a spoken language allowing user to input queries in normal vocabulary/syntax
Computer understands keywords/positions in sentence to get idea of syntax
Will then search database for keyword to provide output or responses.

Use: e. g. On an expert system or search engine. 1 for use, + 2 other -, max 3)

Provides utility programs to allow user to carry out maintenance tasks (any 3)
Provides security measures like passwords and identifications.
Controls the hardware and the operations they allow.
Provides translators to convert software into a form useable by the computer.
Manages interrupts.
To provide a platform for the execution of software (1 per -, max 3)

Data is transmitted along a single wire/one bit at a time.
Data is transmitted along a number of wires/one byte (or more) at a time.
Data can only be transmitted in a single direction.
Data can be transmitted in both directions but only one at a time.

Each byte contains an even number of 1’s A special bit is set to 0 or 1 to ensure that total is even. Byte is checked for even number of 1’s after transmission. (1 per -, max 2)
When two bits are in error the errors cancel each other out/10101001.

Collected data input to system via HCI/automatically
Data input is compared to library of data to find matches…
by inference engine…
Using rules found in rule base
Decisions made about geologic structure reported through HCI. (1 per -, max 4) [4]

Site map

a diagram showing the way the different screens fit together
shows the links between screens,
Gantt chart/progress chart
shows the different parts that need to be developed
shows which parts of the development are independent and which are reliant on each other.

Spider diagram

to show interaction between the different elements of the solution
and those parts which are independent of each other.

Flow diagram

to show the order of producing the parts of the solution
or to show the flow through the proposed site. (Up to 2 groups, up to 2 per group, max 4)

Documentation for owner of site

will be paper based
will contain instructions for changing/maintaining site

Documentation for viewer/visitor to site

will be on-screen
giving detailed help on searches/use of facilities/communication with site owner…

Sound

Music to accompany the pictures/speech to explain the pictures….

Video/animation

Moving pictures to better describe the object on the site
Automatic hard copy/saving
Automatic downloading of data to printer/hard drive for future reference.

Hyperlinks

Allowing access to different sites/parts of site (Up to 2 groups, up to 2 per group, max 4)

Colour:

Contrast
Corporate schemes
Aggressive/passive/soothing colour schemes
Consistency over site to make site look cohesive
Use colour to provide emphasis
Accessability issues e. g. colour blindness

Layout
Consistent layout so user gets used to ‘what is where’. Important things to top and left

Data spread out across whole screen
Tab order
Group similar data together

Content:

Limit to amount of content on a page
Content on a page is cohesive
Content matches the published intentions of the site
Content is of sensible type and reading age for audience. (1 per -, max 2 per group, max 6)

The bit rate is a measure of the rate that data can be sent across the communication medium

Different communication media have different bit rates
For simple text/still pictures…a low bit rate connection is adequate
because volume of data per page is low and fixed
For (live) video/sound…bit rate needs to be high -because large volume of data which must be downloaded in real time because…
information is time sensitive.

Custom written software is especially written/according to the requirements of the customer

Off the shelf is readily available/needs tailoring to the needs of the customer
no delay as it is ready immediately
No shortage of experienced users/ready trained/No learning curve
Software should be error free
Help available through Internet/colleagues/courses
Compatible with other users/software (1 per -, max 2)

Check data input to ensure it matches source data

Typed in twice…
by different people/at different times
inputs checked against each other for errors
manual check by comparing…
screen output of input with original document. (1 for first -, + any 2 other -, max 3)

Check data input is sensible/follows set rules/are reasonable

Data type/should be numeric
Data format/should be in currency form/xxx. xx
Length check/input should be < x characters
Presence check/something has been input.
Range check/value between 0 and some upper limit (1 for first -, + any 2 other -, max 3)