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CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the May/June 2013 series 9691 COMPUTING 9691/13 Paper 1…
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CAMBRIDGE INTERNATIONAL EXAMINATIONS GCE Advanced Subsidiary Level and GCE Advanced Level MARK SCHEME for the May/June 2013 series 9691 COMPUTING 9691/13 Paper 1 (Written Paper), maximum raw mark 75 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 should be read in conjunction with the question paper and the Principal Examiner Report for Teachers. Cambridge will not enter into discussions about these mark schemes. Cambridge is publishing the mark schemes for the May/June 2013 series for most IGCSE, GCE Advanced Level and Advanced Subsidiary Level components and some Ordinary Level components. Page 2 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9691 13 (1) (a) Any one from: collection of systems programs that control the activities of the computer system acts as an interface between user and hardware manages the applications and hardware etc. [1] (b) 1 mark for naming type of real time process + up to 2 marks for description of each type real time transaction (processing)/booking system requires file/database to be updated immediately/prevent double booking examples include airline bookings, theatre bookings real time process control/manufacturing makes use of sensors and feedback loops the output from the system affects the next input examples include monitor/control of a chemical plant [4] (c) Any two points from: for example, a washing machine or microwave oven ROM stores the whole instruction set microprocessor has just one set of tasks to perform system expects simple inputs (e.g. keypad on front of washing machine) the microprocessor has simple, never-changing hardware functions to control [2] © Cambridge International Examinations 2013 Page 3 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9691 13 2 (a) Any four points from: data is transferred from primary memory to hard disk buffer when the buffer is full, the processor can carry on with other tasks hard disk buffer is emptied when hard disk buffer is empty, hard disk sends an interrupt to the processor requesting more data to be sent according to priorities [4] (b) control unit – any two points from: manages execution of instructions fetches each instruction in turn decodes and synchronises its execution by sending control signals to other parts of the processor memory unit – any two points from: stores program currently in use stores data currently in use stores parts of the operating system currently in use [4] © Cambridge International Examinations 2013 Page 4 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9691 13 3 (a) Any four points from: sensors send signal/data to the computer data is converted into digital form/converted by ADC sensor data is then interpreted as seismic data by computer s/ware if data values normal activity (stored in computer files) …. ... then computer sends a signal (which needs to be converted into analogue signal) ... to actuators which sound an alarm ... or to a computer screen and the data is shown as red/flashing/ animation [4] (b) (i) Any three from: graphics on screen interpret the data in easy to understand form data superimposed on map of area being monitored animated circles show seismic intensity on map data is shown in red if it is unusually high the interface should be easy to use/interpret [3] (ii) touch screens trackerball keyboards can easily select graphic on screen by touching screen/moving arrow easy to navigate around the screen to look at data in different areas need to type in data, queries/commands etc. … so keyboard is required [3] © Cambridge International Examinations 2013 Page 5 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9691 13 4 1 mark for each device + 1 mark for description of use large monitor/screen designs can be very complex and it is necessary to have very large screen so the detail can be seen easily light pens if the design team are using CRT monitors, then light pens can be used to draw things, move things on screen, pick up items, etc. plotters to produce very large hard copy outputs; sometimes full size drawings of designs are needed or there is the need to produce a blue print for the manufacturing department space mouse/space ball these are used when doing 3D work in CAD; they allow the manipulation of 3D objects on screen in all 6 directions 3D printers these printers produce solid, working prototypes directly from the drawings Graphics tablet ease of producing the design [6] © Cambridge International Examinations 2013 Page 6 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9691 13 5 (a) Any three points from: sample declaration: MyTable [1:3, 1:6] use of 2-dimensional array (of type) integer use of two nested loops to feed in x-data and y-data data is read in rows or columns corresponding to matrix data given sample algorithm: for x = 1 to 3 for y = 1 to 6 read MyTable [x, y] next y next x [3] (b) value 6 referenced at MyTable [2, 3] [1] (c) Any three points from: scan all the data in the array (row by row or column by column) use of for … to loops to search array check the value in each position in the array if value = 0 then output a message and indicate position in array where erroneous data is stored use of example on exam paper: errors at: [2, 4], [2, 5], [2, 6], [3, 1] and [3, 2] would all be flagged/error message given sample algorithm showing search error indication [3] © Cambridge International Examinations 2013 age Pa e7 Mar M rk Sc S he eme e Syl S labbus s Pa ape er GC GCE AS S/A A LEV L VELL–MMay y/Jun ne 20 2 13 96991 13 6 ( (a) 1m marrk perr co orre ectt lo ogic c gate e (a acc cep pt oth o er log gic ga ate e no omen ncla ature)) A B X C [5 5] ( ) (b) A B C X } 0 0 0 0 0 0 1 1 1 ma mark } 0 1 0 1 1 ma mark 0 1 1 1 1 1 0 0 0 1 0 1 } 1 ma mark 1 1 1 1 0 1 0 1 } 1 ma mark [4 4] © Ca amb brid dge e In nterrnattion nal Ex xam mina atio ons s 20 013 3 Page 8 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9691 13 7 (a) 1 mark for each design feature + 1 mark for factors that need to be considered specify hardware and software if there are large volumes of data this will dictate the type of printer they buy or the type of file access will dictate that they buy a hard disk drive; if they need to do finances then they may need to buy a spreadsheet design data collection forms/screen layouts/report layouts if customers can buy items in the shop then it will be necessary to design good screen layouts which are easy to use; data collection forms may be necessary if there is much paperwork that needs transferring to the new system, for example design data validation routines the type of data that is input will dictate what kind of validation is needed e.g. catalogue numbers when customers order in shop may need format check; file structures may require validation routines (customer records) design the user interface it may be necessary to consider touch screens, use of drop down menus depending on what is decided about screen layouts [8] (b) Any three points from: table showing type of testing, test data, expected results, actual results and comments about results/testing (NOTE: give 1 mark if 2 headings from table given and 2 marks if all 3+ mentioned) test results help systems analyst make judgements comparison made between actual results and expected results if results are not as expected, the system is modified comments on comparisons table help in the overall evaluation [3] © Cambridge International Examinations 2013 Page 9 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9691 13 8 (a) (i) character “A” [1] (ii) column number: 6 row number: 8 [1] (iii) Any three points from: character “A” is showing even parity column 6 is also showing even parity where the column and row intersect is position (6, 8) the bit value here should be 0 and not 1 [3] (b) Any three points from: bytes sent as a block bytes added up before transmission result of addition is sent with the data block same calculation is carried out at receivers end the two values are compared [3] © Cambridge International Examinations 2013 Page 10 Mark Scheme Syllabus Paper GCE AS/A LEVEL – May/June 2013 9691 13 9 (a) Any five points from: if the barcode can’t be read, the number is keyed in using a keyboard the barcode is the key field in the stock file the barcode is searched for in the stock file until a match is found (if no match, error message sent back to POS) If match found, the appropriate record is accessed the price + description of goods is sent back to the POS terminal the stock level in the record is found and 1 is subtracted for each item bought/scanned the new stock level is written back to the file if stock level = re-order value/minimum stock level, then automatic re-ordering takes place the supplier file is accessed to gain necessary information to permit ordering to take place when goods are ordered, a flag is assigned to the item to indicate an order has been initiated this is repeated until all the barcodes in the customer basket have been scanned when new goods arrive, the barcodes on the cartons are read and the stock file is updated accordingly [5] (b) 1 mark for device + 1 mark for reason keyboard to key in barcode numbers if barcodes don’t scan correctly magnetic stripe reader to read loyalty cards/debit cards/credit cards printer to produce itemised bill/receipt for customer speaker/beeper to produce beeping sound to acknowledge barcode has been read OK or to indicate an error when barcode failed to read correctly LCD screen to show prices of good scanned/total cost of goods bought touch screen select item if fresh food bought which may have no barcode [4] © Cambridge International Examinations 2013
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