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Computer technology

Computer technology. The history of computer technology video clip. Low Level Machine. how a computer handles the smallest amounts of data in its processor. Low Level Machine. how data is represented inside the computer. INPUT. Low Level Machine. PROCESS. OUTPUT.

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Computer technology

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  1. Computer technology • The history of computer technology video clip

  2. Low Level Machine

  3. how a computer handles the smallest amounts of data in its processor. Low Level Machine how data is represented inside the computer.

  4. INPUT Low Level Machine PROCESS OUTPUT

  5. INPUT the entering of the data. Low Level Machine Random Access Memory stores the data PROCESS the calculation is done by the central processing unit and the answer is the OUTPUT

  6. The CPU consists of three parts: Low Level Machine Memory to store small amounts of instructions Arithmetic Logic Unit to do the calculations Control Unit controlling the input and outputs of the CPU

  7. Watch a video clip The CPU Low Level Machine Memory ALU Control Unit Input line from keyboard

  8. R A M The CPU Low Level Machine Memory Arithmetic and Logic Unit Control Unit

  9. 01010110 101010b1 01010101 01011 1000 10101110 1001i111 110101010 00010101 11111000 1n110000 11010 0101 10010101 1011011a 001110101 01010101 011011101 010r0101 0111 0101 01011101 11000111 1y100010 b Low Level Machine i n a r y

  10. Binary is also known as machine code, as it’s the code which instructs the machine Low Level Machine Every 0 or 1 is called a binary digit or bit Eight bits represent a character for example, 0100 0001 represents the letter A Eight bits together are called a byte We use the byte to measure capacity of a computers for example, kilobyte, megabyte and gigabyte.

  11. Low Level Machine Eight bits = 1 byte 1 kilobyte = 1024 bytes and is written as 1kb 1 megabyte = 1024*1024 kilobytes or = 1 048 576 bytes written as 1mb 1 gigabyte = 1024 * 1024 * 1024 kilobytes = 1 073 741 824 bytes or 1gb

  12. If the computer has to process data it must store it All data is stored in the computers memory The memory of the computer is measured in bytes Each memory location can hold one byte of data (or a multiple of bytes) Each memory location has an unique address This way of identifying each memory location is called addressability Low Level Machine

  13. One byte 00000001 00000010 00000011 00000100 00000101 00000110 00000111 00001000 00001001 00001010 00001011 00001100 00001101 00001111 memory locations memory addresses 01010011 Each memory location will have its own unique address 11011011 Low Level Machine 11011011 11011011 11011011 11011011 11011011 11011011 11011011 11011011 11011011 11011011

  14. Data travels from input devices to the processor, or between RAM and the processor or to and from the different parts of the processor in groups of bits This group is called a WORD Older computers had a WORD LENGTH of 2 bits this increased to 4 and then 8 now most modern PC’s have a WORD LENGTH of 16, 32 or 64 bits This means that data is passed around much faster and tasks carried more quickly Low Level Machine

  15. The data to be processed 01011100 10101100 01011100 10101100 Low Level Machine A 2 bit machine would transfer the data 2 bits at a time This would mean time for a total of 16 transfers A 8 bit machine would need only time for 4 transfers A 16 bit machine would need only time for 2 transfers A 32 bit machine would need only time for 1 transfer

  16. Doing a simple calculation (and not accurately reflecting) The 2 bit machine is 16 times slower than the 32 bit machine The data being processed will take 4 minutes on the 2 bit machine Low Level Machine and only 15 seconds on a 32 bit

  17. Each character that appears on the keyboard has a special code to represent it consisting of 1s and 0s these are known as alphanumeric characters Each country and language has a special collection of characters and so a collection of characters is known as a character set Computer manufactures have had to standardise on the binary code that they have allocated to each character and the most popular one is the ASCII set Low Level Machine

  18. A American S Standard C Code I Information I Interchange Low Level Machine ASCII allows different Computer systems to communicate with each other because text is represented by the same code

  19. Control Characters control certain operations the computer carries out For example ctrl-p will tell the operating system to print the current screen Other codes may tell the computer to print condensed or take a new line – the return key Control Characters are also represented by ASCII ASCII uses 7 bits and therefore one character set can have up to 127 individual characters Low Level Machine

  20. Graphics on the screen are made up of tiny dots called pixels The more pixels on the screen the better the picture The more pixels – the higher the resolution and the more memory needed to store each pixel In a black and white picture all black pixels would be stored as a 1 and all white pixels as a 0 So high resolution screens and graphics need more memory than low resolution ones Low Level Machine

  21. If we increase the size of this graphic we will begin to see the pixels Low Level Machine Click here to see the graphic at 1000%

  22. 0 0 0 0 0 0 0 0 0 0 0 Low Level Machine 0 0 0 1 1 1 1 1 0 0 0 0 0 1 0 0 0 0 0 1 0 0 Black pixels are represented by a 1 and white pixels by a 0

  23. Binary can represent any number whole and real Low Level Machine The binary number system is a base 2 system Decimal is a base 10 system 128 64 32 16 8 4 2 1 0 0 0 0 0 1 0 1 =5 0 1 0 1 1 0 1 0 =90 1 1 1 1 1 1 1 1 =255 0 1 0 1 1 0 0 0 = 88

  24. Using binary to represent non negative integers is very straightforward Of course numbers larger than 255 will require more than 1 byte to represent them 4 bytes can be used to represent a number this gives the binary number 232 or thirty two 1s 11111111 11111111 11111111 11111111 This is 4,294,967,295 although the top of the range is about half of this to allow for negative numbers Low Level Machine

  25. But what happens when the number is bigger than 2000 million? The computer uses Floating Point Representation also known as standard form or scientific notation FPR is also used to represent real numbers i.e. numbers that are not whole numbers e.g. 51.6784, very small and and very large numbers. In decimal 60 420 000 000 can be represented as 6.042*1010 Low Level Machine

  26. Decimal FPR has four components: Low Level Machine Sign (+ or -) positive numbers are not signed Exponent (10) 6.042*1010 Base (10) Mantissa (6.042)

  27. The sign indicates whether the number is positive or negative The exponent indicates how many places the point has been moved The base indicates the number system being used The mantissa indicates how many places the point has been floated Low Level Machine

  28. In binary the position of the point is always the same The number base is always two All that is needed to be stored is the mantissa and the exponent Low Level Machine Decimal Binary FPR 28.5 = 11100.0101= 0.111000101 * 0101 Mantissa Exponent 111000101 0101

  29. Return to picture at 100% Low Level Machine The pixels are the small squares

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