1Computer Systems are Different!6.033 Spring 2008Static discipline• Be tolerant of inputs and strict on outputsMoore’s law“Cramming More Components Onto Integrated Circuits”, Electronics, April1965Moore’s Law: # transistors/die doublesevery ~18 monthsLithography:the driver behind transistor count• Components/areaO(x2) with feature size• Total componentsO(a) with die area• Switching rate O(x)with feature sizeCPU performance2RAM densityDisk: Price per GByte dropsat ~30-35% per yearENIAC• 1946• Only one• 5000 adds/sec• 20 10-digitregisters• 18,000 vacuumtubes• 124,500 watts• Not really storedprogramUNIVAC (Universal Automatic Computer)• 1951• 46 sold• 2000 ops/sec• 1,000 12-digitwords (mercury)• 5000 tubes• $1.5 millionIBM System/360-40• 1964• 1.6 MHz• 16-256 KB core• $225,000• Family of six• 32-bit• Time-sharingCray 1: supercomputer• 1976• 80 sold• 80 MHz• 8 Mbyte SRAM• 230,000 gates• $5 million3DEC PDP-8 (1964)• 60,000 sold• 330,000 adds/sec• 4096 12-bit words• $18,000Apple II• 1977• 1 MHz• 6502 microprocessor• 4 to 48 Kilobytes• $1300• Basic, VisicalcIBM’s wrist watch• 2001• Linux and X11• 74 Mhz CPU• 8 Megabyte flash• 8 Megabyte DRAM• WirelessSoftware follows hardwareMillions of lines of source codeCheap → PervasivePervasive → qualitative changeyearlog (people per computer)Slide from David Culler, UC BerkeleyNumber crunchingEmbeddedSense/controlWord processingCommunication4Latency improves slowly11010010001 2 3 4 5 6 7 8 9 10 11Year #Improvement wrt year #1Moore’s law (~70% per year)DRAM access latency (~7% per year)Speed of light(0% per year)Incommensurate doublingHeat is a problemRecent Intel CPU Clock Rates486PentiumPentiumProPentium IIIPentium 4Pentium 4 HTmHzThe Future: will it be painful?AMD Barcelona Quad-core chipWhat went right?• Unbounded composability• General-purpose computers• Only need to make one thing fast• Simple interface, complex implementation• Decouple software from CPU• Cumulative improvement over
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