ICT unit 4 representing data
A Coggle Diagram about Images and sound (Sound is an analogue form so to transfer sound to a computer it needs to be digitally sampled, The more poi the more data to be sobered and the larger the file, The resolution is the number of pixels per unit, for example the number of pixels per inch, Sound files are described by metadata to make sure the computer can interpret data accurately, The more bits per pixel the bigger the colour depth of an image, The data stored also includes the audio codec and the sample rate, The number of bits we use for a pixel determines the number of colours an image has, The higher the sample interval the lower the sample rate, A pixel is one dot in the image, A bitmapped image is displayed enlarged on screen the actual image size does not change, the dots just get bigger and the image becomes pixelated or 'blocky', Metadata is databout data,, The sample interval is often used to describe the sample rate and its is the time between samples being taken, The computer knows how to turn these digits into the image because the file with the binary data contains metadata. , When sound is sampled at a very low rate very few samples are taken, there's poor match between the oringinal sound and the sample sound and a small size file is required, Images are stored in binary on a computer, The bit rate is the amount of space used for each sample, a high bit rate means more accurate sampling at each point which gives better quality and the size is bigger as more data needs to be stored, When sound is sampled at a higher rate many more samples are taken, there is a good match between the original sound and the sample sound and the size of the file is big. and a typical MP3 track is stored at 128kb per second while a CD uses 1411kb per second), Characters (The computer looks up the symbol matching the code from a list of codes and their associated characters, The list of codes and matching characters is the character set of a computer, All the symbol displayed by a computer are represented by a code, The codes used are stored in binary, The number of bits used to store the code determines how many characters or symbols can be used, |Unicode keeps the same 127 ASCII codes so ASCII could now be considered a subset of unicode, ASCII uses 7 bits so can provide 127 characters or symbols plus the null character, Unicode uses 16 bits providing 65000 possibilities or 32 bits providing 4 billion and Extended ascii uses 8 bits providing 256 probabilities), instructions (The instruction is in two parts: The operator: the instruction part, The operand: The data part, The operand represents the data that the operator uses, The CPU fetches this instruction and decodes it in order to find out what to do next, The accumulator is a special register in the CPU used to store results of any calculation, When a computer is instructed to run a program it is directed to a specific location in memory that contains the first instruction in the program and The CPU cannot tell the difference between data and the instructions and simply deals with what it finds according to what it expects to find), Numbers: (Units, Adding binary numbers, Denary to binary, From binary to denary and All data and instructions are in binary, each digit in a binary number is called a bit) and Hexadecimal numbers (Hexadecimal is used because it is easier to represent large numbers with it and to remember them, To convert them into denary we multiply the second digit by 16 an we leave the first as it is.
For example 27 in hex would be 16*2+7=39 in hex, To convert from decimal to ex we have to divide by 16 and if we have a remainder we write that as it is. and From binary to hex we must divide the number in two nibbles and write the value in each nibble)