EDWARD'S LECTURE NOTES:
More notes at http://tanguay.info/learntracker
C O U R S E
The Computing Technology Inside Your Smartphone
Dave Albonesi, Cornell University
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C O U R S E L E C T U R E Inside the Snapdragon 805 Chip Notes taken on June 28, 2016 by Edward Tanguay |
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a look inside a smartphone
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contains a Snapdragon 805 chip from Qualcomm Corporation
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smartphones that have a Snapdragon 800, 801 or 805
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Nexus 6 smartphone
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released by Google and Motorola in 2014
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logic board
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many components
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Snapdragon 805 package
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one component is actually one stacked on top of another
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underneath
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the 805 chip is inside the package to hold the chip
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on top of that is a memory chip
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flash memory chip
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where apps are stored
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Snapdragon 805 chip
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size of fingernail
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SoC design (Systems-on-Chip)
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single chip contains pretty much an entire computer system
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specialized processing engines
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general purpose processor
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the processer that runs your apps
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Qualcomm makes their own processor called Krait
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contains four CPUs
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called "cores"
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each CPU can run an individual app or different portions of an app
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controllers
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get information to and from memory
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which is on top of the Snapdragon 805 package
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handle specific tasks
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GPU
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handles screen graphics
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Adreno 420 GPU
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display engine
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transfers the graphic information to your screen
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playing ultra-high definition video and music
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supports 4K video
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ISPs (Image Signal Processors)
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handling input from the two cameras
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specialized processors for handling sensor inputs
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GPS controller
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USB: Universal Serial Bus
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engineering standard for doing communication through wires
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connect smartphone to laptop
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overlay block
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for communication
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e.g. with cell towers
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overlay because in the 800 and 801 they are on the SoC (System on a Chip)
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but on 805 these are on a separate chip
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trade-offs
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better handles 4K than the 800 and 801
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evolving communications standards, so you take some functionality off of the main chip
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how chip operates when accomplishing a complex task, e.g. playing a game
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the four Krait Quad Core CPU
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orchestrate game play
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handle artificial intelligence of non-player characters
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handle animation and physics of collisions and particle movement
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GPU
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lightings, shadows, reflections
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digital signal processor
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processes audio files
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video decoder
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system memory
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has files which is kept above the 805 chip
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display engine
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specialized unit on 805 chip
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reads the information generated by the GPU and video decoder and sends it to the display
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advantages for organizing the SoC in this way
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performance
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parallelism
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all processors working at the same time on their tasks
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energy efficiency
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better to have a specialized video decoder than to perform those functions on the generalized CPU
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you can save over half of the energy by having specialized hardware
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details of the Krait CPU
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the stack from bottom to top
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digital logic
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transistors and wires
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may have billions
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put together in logic gates
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to select two values
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to store numbers
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to create controllers which orchestrate the flow of data through the computer
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computer organization
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application programs
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instruction set called ARM (Acorn RISC Machine)
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a kind of reduced instruction set computing (RISC)
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add and subtract
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hardware design
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micro architecture
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instruction fetch
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instruction decode
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operand fetch
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execution
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pipelining
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superscalar
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SIMD