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Ubiquitous Presenter up.ucsd

Learn about addressing modes in computer programming and how to achieve increased performance. Explore the impact of improvements using Amdahl's Law. Discover the differences between Pentium III and Pentium 4 processors. Also, find out the top 3 places you most and least want to visit.

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Ubiquitous Presenter up.ucsd

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  1. Ubiquitous Presenterhttp://up.ucsd.edu Beth Simon William Griswold and the UCSD UP development team

  2. Addressing Modeshow do we specify the operand we want? Immediate #25 The operand (25) is part of the instruction R3 (sometimes written $3) The operand is the contents of register 3 M[R3] Use contents of R3 as address into memory; find the operand there. This is a special case of... M[R3 + 160] Add the displacement (160) to contents of R3, look in that memory location for the operand • If register is PC, this is “PC-relative addressing” All our example ISA’s have the above modes Register (direct) Register (indirect) Base+Displacement One other used for jumps, in the book psuedodirect

  3. How do we achieve increased performance?(Gene) Amdahl’s Law IBM • The impact of an improvement is limited by the fraction of time affected by the improvement. • If you make MMX instructions run 10 times as fast, a program which doesn’t use MMX instructions will not run faster. ETnew = ETold affected/amount of improve + ETold unaffected ETnew = 0sec/10 + 100sec  ET new = 100sec Etnew = 50sec/10 + 50 sec  Etnew = 5+50 = 55

  4. SPEC on Pentium III and Pentium 4 --doubling the GHz doesn’t double the SPEC number --Bigger imporvement on P4 on FP SSE2 instruction set – stack registers to regular FP register set Had to recompile to use these instruction sets • What do you notice?

  5. Which of these things is not like the other? Mention Sesame Street B A D C Why?

  6. Label the following 3 things: Epidermis Dermis Fat Cells

  7. What are the top 3 places you most want to visit? What are the top 3 places you least want to visit?

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