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CAMBRIDGE IGCSE COMPUTER SCIENCE PAPER #1EXAM QUESTIONS WITH COMPLETE ANSWERS
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CAMBRIDGE IGCSE COMPUTER SCIENCE PAPER #1EXAM QUESTIONS WITH COMPLETE ANSWERS
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CAMBRIDGE IGCSE COMPUTERSCIENCE PAPER #1EXAM QUESTIONS
WITH COMPLETE ANSWERS
Denary number - answer-a base 10 number in which each digit is worth 10 times the
digit to its right, and digits can have 10 values : 0 to 9
Right, 16 - answer-hexadecimal number
A base 16 number in which each digit is worth 16 times the digit to its ____________,
and digits can have _____ values : 0 to f
4 - answer-the number of bits needed to store a hexadecimal digit
Bit - answer-a single true/false value (short for binary digit)
Debug - answer-to find errors in software
Digital - answer-any quantity that has a precise, discrete value that can be represented
as a number (but cannot assume a continuous range of values)
Byte - answer-a group of 8 bits
Nibble - answer-a group of 4 bits (half a byte, equivalent to one hex digit)
Kilobyte - answer-1024 bytes = 2^10 bytes
Megabyte - answer-1024 kilobytes (2^20 or roughly 1 million bytes)
Gigabyte - answer-1024 megabytes
A,b,c,d,e,f - answer-digits in hexadecimal that are equivalent to 10,11,12,13,14,15
Colour, addresses, machine, memory - answer-*uses of hexadecimal numbers*
___________codes in html
-media access control (mac) and ip _____________
-assembly language and ____________ code
_____________ dumps
-specifying memory locations
Memory dump - answer-an output of memory contents onto the printer or screen.
Usually represented in hexadecimal.
,Mark-up language - answer-a language used when processing and presenting text, e.g.
Html.
Not a programming language but contains information on how text should be structured
and presented (e.g. Paragraphs, colour, font, underlining etc.) And can also be used to
embed images, hyperlinks etc.
Unique, hardware, 48, manufacturer, serial - answer-mac address
A _______________ identifier number that identifies a device on a local area network
(lan).
The address is typically *static* and set in the ____________ by the manufacturer.
The name is an acronym from *media access control*
Structure:
-consists of _____ bits displayed as pairs of hexadecimal.
-the first part is the ____________________ id, the second part is the ____________
number
Digit, parity, repeat - answer-*methods of data verification*
For short numbers (e.g. Credit cards, isbns):
-check ____________
For transmission of more data, over a network:
-______________ bit/checks
-checksum
-automatic _____________ requests (arq)
Repeat request., notification, received, re-sent - answer-automatic ________________
_____________ (arq)
A method of data transmission employing an error-detecting code so that any error
detected by the receiver initiates a repetition of transmission of the incorrectly received
message.
The sender also requests a _______________ that the data has been
________________ correctly.
If no delivery notification is received the message is ____________ periodically until
either it has been safely delivered or a time-out is reached.
,Instructions, digital musical instruments, synthesizer - answer-*midi (musical instrument
digital interface)*
A set of standards / file format used to represent music in digital form. Used for
recording / generating synthesizers and other digital instruments
Midi files
• contain _________________ of how to make sound
• non-audio recording
• file created using ____________ ____________ ________________
• produced by ____________________
• used when composing music
• individual notes/instruments can be changed
Sampling rate, sampling resolution, lossy, repeated, indexing - answer-*sound
sampling*
The _____________ ____________ is the number of times per second the sound wave
(i.e. Pressure, or the analogue signal from microphone) is sampled
The ____________ ____________ is the number of discrete levels that the analogue
signal is converted to.
The analogue signal from the microphone must be converted to digital by adc.
to compress the file by __________ compression, both of these can be reduced.
To compress with lossless compression we could use run-length or huffman encoding.
(i.e. Build a table of ____________ values and represent the data by ___________ into
that table
Wav - answer-(waveform audio file format) an audio coding format standard for storing
an audio bitstream of *uncompressed* audio data.
This is a high quality audio file format used for professional music / broadcasting and
needs very large file sizes
Mp3 - answer-a standard format for music files sent over the internet that compresses
music.
Not as high quality as wav but has much smaller file sizes.
Commonly used in personal music players / ipods.
• digital recording of sound (samples/resolution)
• produced by recording software / microphone
• used when distributing sound files
• compressed file format (lossy)
, Jpeg - answer-the most common graphic file format, full colour graphic format (16.7
million colors) with a relatively small file size
A standard image format for containing compressed image data. This results in good
reduction in file size and maintains reasonable image quality. Commonly used by digital
cameras, phones.
The compression is lossy
Mp4 - answer-mpeg 4; a compressed file format that can be used for audio or video;
appropriate for streaming
The compression is lossy
Compression algorithm, can, repeated, dictionary - answer-*lossless compression*
A data compression algorithm that allows the original data to be perfectly reconstructed
from the compressed data.
A _______________ _________________ is used
No data is lost in the compression process. The original data _____ be recovered
For string/text messages:
________________ words / patterns are identified and are *indexed*/put into a table.
-words are replaced with their *index*. Their positions and the number of times the
word/pattern appears is stored in the table.
For images:
-a ________________ of pixels is created
-the number of times a pixel is repeated in a row is stored and represented by run-
length encoding
For sound:
Repeating sampling levels are put in a dictionary and the signal is represented by run-
length encoding
Compression algorithm, cannot - answer-lossy compression
Data compression where there is some loss of information or reduction in quality : the
resulting files are smaller but
A __________________ __________________ is used
Some data is lost.- the original data _______________ be reconstituted.
Images/video:
Reduce the colour depth and pixel resolution
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