Bits and Bytes (Nianxu) Data has No Meaning Data is in formation that has no meaning. If someone walks up to you and gives you a piece of paper with '120987 written on it, the number could mean absolutely anything. It could be their birthday, or how much money you owe them. Data only becomes in format ion when you know the context of the data.
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1) Computers are machines that process data. They're stupid - they don't understand the data they process. 2) If you get a computer to process data that's incorrect, the results will be meaningless. E.g. If you program a computer to work out the total cost of buying fifty pizzas at £2.99 each, but you type in £29.9 by mistake, you'll get the wrong answer. This is called Garbage In, Garbage Out (GIGO). 3) Some people call this 'computer error'. They're wrong - it's human error. Computers hardly ever make mistakes. They just do what they're programmed to do. ------------------------------------------------------------------------------------------------------------
Data is stored in Bytes Computers run on electricity - try using a computer without it. They consist of a number of electric circuits, and each circuit can be in one of only two states - on or off. 1) Computers use a binary code (i.e. they use only 2 digits) to represent data.
Usually a circuit that's switched on represents the digit 1, and one that's switched off represents the digit 0. (Morse code works ill a similar way - it's either a dot or a dash.)
A binary number is either a 0 or a 1 and is known as a 'bit' or b inary dig it . 2) Characters can be represented by an 8·bit (i.e. 1 byte) ASCII code (pronounced ASSKEY). For example a letter or number could be represented by 01000100. (=1 byte)
The word Hazel would take 5 bytes of memory to store.
File Photo Song Film
File size 3MB 5MB 700MB
A file’s size can be influenced by a number of factors but ultimately the more information a file stores, the larger it will be.
Questions More information on Bits and Bytes: http://www.teach-‐ict.com/gcse/hardware/storage/miniweb/storage_capacity.htm 1. What are the usual capacities of other storage mediums? A few GB Memory stick, CD / rewriter, DVD / rewriter, external hard drive, Blu-‐ray, Magnetic tape, RAM, VCD, SD cards 2. How much memory is used by the word Gary? 4 bytes 3. What comes after gigabyte? Terabyte 4. If a memory card stores 1GB… how many photos (based on the photos being 3mb) can you store on it? 341 photos 5. A hard drive stores 1TB how many movies can you fit on it? (based on 700mb per movie) 1497 movies
6. Avatar the movie on Blu-‐ray is 10.43GB in size how many movies of this size could you fit on a 2 TB drive? 196 movies Complete this quiz (let your teacher know your score) http://www.teach-‐ict.com/gcse/hardware/storage/miniweb/quiz.htm