# A-level Computing/AQA/Problem Solving, Programming, Data Representation and Practical Exercise/Fundamentals of Data Representation

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 From the Specification : Binary number system Pure Binary Representation of Denary Integer Describe the representation of unsigned denary integers in binary. Perform conversion from denary to binary and vice-versa. Binary Arithmetic Add two binary numbers and multiply two binary numbers. Representation of signed integers by Two’s Complement Describe the use of Two’s Complement to perform subtraction. Convert a denary integer into Two’s Complement and vice versa. The Concept of Number Bases: Denary, Binary and Hexadecimal Describe the conversion of a denary integer to hexadecimal form and vice versa. Describe the use of hexadecimal as shorthand for binary. Integers and Numbers with a Fractional Part Draw a distinction between integers and numbers with a fractional part in a computer context.Describe how an unsigned denary number with a fractional part is represented in fixed-point form in binary.
 From the Specification : Information Coding Schemes Describe standard coding systems for coding character data. Understand ASCII Understand Unicode Differentiate between the character code representation of a denary digit and its pure binary representation. Error checking and correction Parity bits, Hamming code. Gray coding Describe Gray coding. Explain why and where it is used.
 From the Specification : Representing Images, Sound and other data Images Describe how bit patterns may represent other forms of data including graphics and sound. Bitmapped Graphics Bitmaps: resolution, colour depth and simple bitmap file calculations. Vector Graphics Vector graphics: drawing list – objects and their properties. Compare bitmaps to vector graphics; advantages, disadvantages. The need for compression and basic techniques for compression. Sound files The need for compression and basic techniques for compression. Sampled Sound and Nyquist-theorem Sampling resolution, sampling rate. Sound Synthesis Describe MIDI and its advantages for storing sound digitally. Streaming audio Explain what it is and why it is used. Analogue and Digital Data. Analogue and Digital Signals Differentiate between analogue and digital data and analogue and digital signals. Analogue to Digital Converter (ADC) Describe the principles of operation of an analogue to digital converter.