UNIT 3: DATA.

3.1 Binary
3.1.1 Understand that computers use binary to represent data (numbers, text, sound, graphics) and program instructions.
3.1.2 Understand how computers represent and manipulate numbers (unsigned integers, signed integers (sign and magnitude, two’s complement)).
3.1.3 Be able to convert between binary and denary whole numbers (0–255).
3.1.4 Understand how to perform binary arithmetic (add, shifts (logical and arithmetic)) and understand the concept of overflow.
3.1.5 Understand why hexadecimal notation is used and be able to convert between hexadecimal and binary.
3.2 Data representation
3.2.1 Understand how computers encode characters using ASCII and Unicode.
3.2.2 Understand how bitmap images are represented in binary (pixels, resolution, colour depth). 3.2.3 Understand how sound, an analogue signal, is represented in binary.
3.2.4 Understand the limitations of binary representation of data (sampling frequency, resolution) when constructed by the number of available bits.
3.3 Data storage and compression
3.3.1 Understand how to use and convert between binary and denary multiples (as defined by the International Electrotechnical Commission (IEC)): • bit • nibble • byte • kibibyte (KiB) 210 • mebibyte (MiB) 220
3.3.3 Understand how a lossless, run-length encoding (RLE) algorithm works. 3.3.4 Understand that file storage is measured in bytes and be able to calculate file sizes.
3.4 Encryption • gibibyte (GiB) 230 • tebibyte (TiB) 240 • kilobyte (kB), 103 • megabyte (MB) 106 • gigabyte (GB) 109 • terabyte (TB) 1012.
3.3.2 Understand the need for data compression and methods of compressing data (lossless, lossy), and that JPEG and MP3 are examples of lossy algorithms.
3.4.1 Understand the need for data encryption.
3.4.2 Understand how encryption algorithms work (Pigpen cipher, Caesar cipher, Vigenére cipher, Rail Fence cipher).