Computer Science Revision (PAPER 2)

• Created by: Kani.T
• Created on: 11-04-18 19:57
Bit Rate
The number of bits to store one second of sound
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Bit Rate Formula
Frequency x Bit Depth x Channels
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Machine Code instructions
Where an operator (op-code) tells the computer what to do (e.g. Load/Store); the operand tells the computer what to do with the instruction
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Nyquist's Theorem
The sample rate should be at a frequency which is at least twice the value of the highest frequency in the sampled signal
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Logic Gates
A logic gate is an elementary building block of a digital circuit
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NOT gate
This gate inverts the input and is represented by an overbar
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AND gate
Where the output of A AND B is 1 only if input A and input B are both 1
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OR gate
Where the input is always 1 unless both inputs are 0
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XOR gate
AKA: Exclusive OR- this is where the output is true if one or other input is true, but not both
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NAND gate
Inverts the output of an AND gate
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NOR
This gate only produces an output of true when both outputs are false
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De Morgan's First Law
NOT(A OR B) = NOT(A) AND NOT(B)
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De Morgan's Second Law
NOT(A AND B) = NOT(A) OR NOT(B)
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General Rules of Boolean Algebra
X.0 = 0 | X.1 = X | X.X= X | X.NOT(X) = 0 | X + 0= X | X+1= 1 | X+X= X | X+NOT(X)= 1 | NOT(NOT X)= X
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Commutative rules
X.Y = Y.X | X+Y= Y+X
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Associative rules
X. (Y.Z) = (X.Y) .Z | X+ (Y+Z) = (X+Y) +Z
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Absorption rules
A+ (A.B) = A | A. (A+B) = A
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Subroutine
A named block of code designed to carry out a specific task
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Procedure
Another term for a subroutine
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Local Variable
A variable that is only available in specified subroutines and functions
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Global Variable
A Variable that is declared at the beginning of the program and is available anywhere in the program
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Function
A subroutine that returns a value
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Functional Programming
A programming language that uses functions to create programs
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Parameter
Data being passed into a subroutine
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Arguement
An item of data being passed into a subroutine
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Exception Handling
The process of dealing with events that cause the current subroutine to stop
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Hierarchy Chart
A diagram that shows the design of a system from the top down
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Flowchart
A diagram that shows individual processes within a system
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Pseudocode
A method of writing code that does not require knowledge of particular programming language
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Laser scanners
How it works: reflects off a moving mirror which allows the barcode to be read in many different positions
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A chip that consists of a small microchip transponder and an antenna- used to track and identify things such as households products
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Laser Printer
Offers high-quality, high-speed printing; their function is similar to that of a photocopier using powdered ink called toner
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Hard Disk
Uses rigid rotating platters coated with magnetic material
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Optical Disk
Works by using a high powered laser to 'burn' sections of its surface, making them less reflective
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Solid-state Disk (SSD)
A storage device that uses integrated circuit assemblies as memory to store data persistently
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Cyber attack case study
In 2007, Estonia suffered a series of cyber attacks which swamped websites of organisations including the Estonian Parliament, banks, newspapers and broadcasters.
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Abstraction
A technique for arranging complexity of computer systems (simplifying it)
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Machine Code
A first generation language that only a computer can understand (1s and 0s)
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Other cards in this set

Card 2

Front

Frequency x Bit Depth x Channels

Bit Rate Formula

Card 3

Front

Where an operator (op-code) tells the computer what to do (e.g. Load/Store); the operand tells the computer what to do with the instruction

Card 4

Front

The sample rate should be at a frequency which is at least twice the value of the highest frequency in the sampled signal

Card 5

Front

A logic gate is an elementary building block of a digital circuit