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Computing F451
Hardware and software
o Hardware
Physical components of a computer system
o Software
Programs which provide a platform between the user and the
hardware, allowing the user to do something useful with the
computer
o Input Device
A device which allows a user to tell the computer what…

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Allows analyst to know what errors need to be rectified in the
new system
o Analysis
A specification is drawn up from the results of the problem
definition, feasibility study and information collection.
Outlines what the designer must take into consideration, and
what the aim of the system must be.…

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o Spiral and Waterfall Models for systems life cycle
The above list of 9 stages works in a loop, once the new
system is being maintained a new problem may arise and the
lifecycle may begin again. However, if something goes horribly
wrong, let's say at the design stage we…

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processes them all at once, without user input
during processes.
o E.g., workers registering at the start of the day,
or calculating the pay for workers, for their
hours worked.
Multi tasking, single user
o Allows one user to use the system at any one
time.
o Allows multiple applications…

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Command-line
o Requires user to type in commands which the
system understands. User has access to entire
system but needs specialist knowledge to be
able to operate it properly.
Natural Language
o Computer understands human language.
Commands either typed into computer or
spoken to it are understood by the computer…

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Uses base 2 (1's and 0's)
Because computers run on electrical signals which can either
be on (1) or off (0)
Bit = one 1/0
Nibble = 4 1/0's
Byte = 8 1/0's
Word can = 16 1/0's
Column headings are in base 2: ...128,64,32,16,8,4,2,1
Therefore the number 00000001 =…

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1+1+1=1, carry1
E.g. 01001011
+10010011
=11011110
Run through the above calculation, checking each column for
which of the 4 rules was used.
o Negative binary
Negative numbers can be represented in two ways. One uses a
sign of magnitude like our denary system. The column headings
become: +/-...64,32,16,8,4,2,1
So 10000001…

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MICR - Magnetic Ink Character Recognition is another method
of detecting ASCII characters. It works by detecting magnetic
traces in the ink (it is printed using special magnetic ink) and
interpreting the shape of the characters, once again converting
them into ASCII.
Barcodes are read by a laser scanner which…

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The Memory Address Register keeps a temporary storage of
where data has come from and where it is going to.
o MDR
The Memory Data Register is where temporary data can be
stored to increase the speed of computer processes.
o PC
The Program Counter keeps track of the next…

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Data that is not stored in the system memory is stored in
secondary storage
The HDD (Hard drive disk) is probably the main storage on a
computer. It can be used to store large amounts of user files,
however it is much slower to transfer data between it and the…

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