Binary! Objectives

1. Binary!Objectives • Understand that all data on a computer is stored in binary • Look at the untis of measurement for computer data • Bit • Byte • Nibble • Kilobyte • Mega / giga / tera byte

2. BinaryNibble Computers work in binary. We found out why in the hardware section (lesson 5). Can you remember why? Computers work much more reliably by using binary. All data, regardless of what it is, will be stored in binary. Images, music, sound effects, movies, text and programs are all stored in binary. How is this possible? How can the values 1 and 0 represent so many different things. When a virtual object, such as a image, is represented in binary it is said to be encoded. By clever usage of encoding schemes we can represent anything!

3. BinarySimple encoding Imaging giving directions to someone. Let’s say they follow a direction until they reach a turning. They then follow the next instruction and so on until they get to their destination.

4. BinarySimple encoding We would go east,

5. BinarySimple encoding We would go east, north

6. BinarySimple encoding We would go east, north, east

7. BinarySimple encoding We would go east, north, east, east again,

8. BinarySimple encoding We would go east, north, east, east again, east one more time

9. BinarySimple encoding We would go east, north, east, east again, east one more time and finally north

10. BinaryEncoding directions • So we went • East • North • East • East • East • North • We could say, for short, • ENEEEN • Where E is east and N is north

11. BinaryEncoding directions in binary There are 4 directions N - 1 S - 2 W -3 E -4 We can encode each of these as a number. That gives us the number 414441 for our direction. Finally we can assign a binary value to each direction instead of a number or letter N – 00 S – 01 W – 10 E – 11 So our direction of ENEEEN would be 11 00 11 11 11 00

12. BinaryActivity Using the map below encode directions to go from a starting point to a end point of your choice. Then swap with your neighbour to see if they can follow them!

13. BinaryBits, bytes and nibbles The smallest unit on a computer is called a bit. This can store a single binary value (or a 1 or 0). A byte is made up of 8 bits. As bits are very small computers tend to work in bytes more often than not. A nibble is half a byte (or 4 bits). Historically a byte was the size needed to encode a single letter on a computer (which could vary from computer to computer). Over time it was decided to fix the size of a byte to 8 bits as this was convenient for hardware and software developers.

14. BinaryKilobyte, mega byte, giga byte and tera byte The word kilo comes from the greek word khiloi which means 1000. A kilometre is 1000 meters. A kilolitre is, you guessed it, is 1000 millilitres. A kilobyte, however, is 1024 bytes! Why is a kilobyte not 1000? The reason is to do with binary and based on the powers of two. 1024 is 210 . It again makes computer hardware much simpler. 1 megabyte = 1024 kilobytes (220) 1 gigabyte = 1024 megabytes (230) 1 terabyte = 1024 gigabytes (240) The short hand for each of the above is – Megabyte = MB Gigabyte = GB Terabyte = TB

15. BinaryActivity How many bits are there in 1.5 terabytes? A mp3, on average, is 4MB (4 megabytes) in size. How many songs can you store on a iphone 32GB assuming you could use 100% of the storage. Make notes on the units of computing in your revision PowerPoint.