Computers: How They Work

1. Computers: How They Work What is a Computer Components of Computer World’s First Computers and CPUs Mother Board Machine Code and the processor’s Instruction Set – Software Memory types (ROM, DRAM, SRAM, FLASH) Hard Drive Compact Disk Keyboard Monitor The Mouse Other I/O DSL and connection to Internet File Compression

2. Demonstrations PC Mother Boards Memory Hard Drive Magnetic Tape Punch Cards CDs SIMM cards Polarized Films LCDs Keyboard CCD chips

3. What is a Computer? A machine that stores instructions and data and operates on information/data.

4. http://www.sscnet.ucla.edu Jacquards Loom Circa 1804

5. Charles Babbage’s first attempt at a Computer The Analytical Engine, c. 1822 Designed to use Jacquard punch cards to store and run a program Mathematician, Augusta Ada Lovelace, created programs Steam Powered 25,000 parts 15 tons and 8 feet high Never completed http://concise.britannica.com

6. Difference Engine II • Designed to calculate polynomials and compute trig and log functions • C. 1847 • Crank operated http://www.computerhistory.org/babbage/

7. Microprocessor • A logic machine that can execute a a small set of instructions. • A Central Processing Unit (CPU) integrated into a single chip (i.e. constructed as an integrated circuit on a single piece of Silicon) http://en.wikipedia.org/wiki/Central_processing_unit

8. Components of a Computer Processor Memory Input/Output Processor Memory (ROM, RAM, Registers, Cache) Output (Monitor, speakers, USB Drive, Printer, DSL, Hard Drive) Input (Keyboard, Mouse USB Drive, DSL, Touchscreen, Microphone, Hard Drive) USB – Universal Serial Bus DSL – Digital Subscriber Line

9. What’s Inside a basic CPU?(Central Processing Unit) ALU (Arithmetic Logic Unit) Performs addition, division, etc. Instruction Decoder Program Counter Instruction Register – stores current instruction being worked on. Data Registers – stores current data being worked with. Accumulator (place for storing a sum) Clock for sequencing operations

10. Memory – A Device that “remembers” a previous input. Registers are the high speed memory on the CPU chip. These registers are used for storing data that is frequently needed. Instructions are pre-fetched and stored in registers too so that they are ready when needed.

11. 4004 Intel Processor Registers

12. 1-bit Latch (Flip Flop) Static RAM and registers are constructed with this logic. The state of Q is retained as long as power is on. Static RAM –Non-volatile Random Access Memory

13. 4-word Static RAM

14. Memory Hierarchy http://www.surriel.com/lectures/hierarchy.gif

15. Cache Memory http://content.answers.com

16. SRAM Static Random Access Memory Retains data in memory as long as power is on Uses flip flops (8 transistors each) Fast but more expensive due to more chip real-estate needed for each memory location compared to DRAM Used for cache memory Fast Access time  10 nanoseconds

17. DRAM and SDRAM Dynamic RAM Dynamic refers to the need to refresh the data Synchronous DRAM (Timing of memory chip is synchronized with CPU clock) Data is stored as electrical charge in capacitors Capacitors will discharge requiring that memory be refreshed every few milliseconds. Dense therefore least expensive form of memory http://www.electronics.dit.ie/staff/tscarff/memory/ram.htm

18. The word “random” means bytes can be accessed randomly. Data access is not sequential like a magnetic tape. http://www.cse.scu.edu

19. SIMM & DIMM Single In-line memory module Dual In-line memory module These cards are DRAMS http://en.wikipedia.org/wiki/DIMM

20. ROM of three memory locations, each “word” of memory is 3 bits Read Only Memory Data contents can not be changed Data retained even when power is off Manufactured with the data Used for booting up computer and loading Operating System Device Driver software Diodes http://www.compeng.dit.ie

21. http://tams-www.informatik.uni-hamburg.de

22. Flash Memory • (Electrically Eraseable Programmable Memory) • Using Floating Gate Transistors to store bits • Non-volatile (power not needed to maintain data) • MP3 Players are flash drives with extra circuitry to decode data to analog music signals • Cellular Phones • Digital Cameras • Very resistant to temperature, shock, field stress http://electronicdesign.com/Articles/ArticleID/16383/16383.html

23. Hard Drive120-240 GBytes Data stored magnetically Permanent Storage, Non-volatile memory Fast - Spins 4,500 to 12,000 rpm Dense and Inexpensive Data easily erased and rewritten Iron Oxide or very thin magnetic film applied with a sputtering process stores magnetic data Not random access http://www.metallurgy.utah.edu/

24. Actuator Platter Actuator Arm Spindle Read/Write head

25. Read-Write Head Multiple Platters Head 20-50 nm from platter surface A human hair is 100 nm How Stuff Works wikipedia www.hddtech.co.uk

26. The voice-coil actuator controls the movement of the actuator arm • Positions the read/write heads • Similar to a speaker! • Uses a coil and permanent magnet • Converts electrical signals into mechanical movement • In this picture, magnet has been moved to the left during disassembly to expose the coil • Coil moves freely under the magnet http://www.storagereview.com/guide2000/ref/hdd/op/over.html

27. Small Tolerances 5-80 Mbytes/sec media transfer rate

28. Software commands Hardware while (amt2 <= amt1) { amt1 = amt1 + 100; amt2 = amt2 + 0.05*amt2; year++; } 14: while (amt2 <= amt1) 004015BB fld dword ptr [ebp-8] 004015BE fcomp dword ptr [ebp-4] 004015C1 fnstsw ax 004015C3 test ah,41h 004015C6 je main+70h (004015f0) 15: { 16: amt1 = amt1 + 100; 004015C8 fld dword ptr [ebp-4] 004015CB fadd dword ptr [__real@4@4005c800000000000000 (0046f0a4)] 004015D1 fstp dword ptr [ebp-4] 17: amt2 = amt2 + 0.05*amt2; 004015D4 fld dword ptr [ebp-8] 004015D7 fld dword ptr [ebp-8] 004015DA fmul qword ptr [__real@8@3ffaccccccccccccd000 (0046f098)] 004015E0 faddp st(1),st 004015E2 fstp dword ptr [ebp-8] 18: year++; 004015E5 mov eax,dword ptr [ebp-14h] 004015E8 add eax,1 004015EB mov dword ptr [ebp-14h],eax 19: } C++ high level codes gets compiled/translated into low level machine codes

29. Fetch-Decode-Execute Cycle • Fetch an Instruction: • Fetch instruction at address stored in address register • Increment Program Counter • Load the Instruction Register with this Instruction

30. Decode • Decode the Instruction • Fetch the operands • Execute • ALU or other logic performs the operation • The result is then written to memory or to a register.

31. A Computer is much more than a processor…. Processor Intel® Core™2 Q6600 Quad-Core (8MB L2 cache,2.4GHz,1066FSB) Video Cards 768MB nVidia GeForce 8800 GTX Memory 2GB* Dual Channel DDR2 SDRAM at 667MHz - 2 DIMMs Hard Drive: 500GB* - 7200RPM, SATA 3.0Gb/s, 16MB Cache Optical Drive Single Drive: Blu-ray Disc Drive (BD/DVD/CD burner w/double layer BD write Monitors 20 inch E207WFP Widescreen Digital Flat Panel http://www.dell.com

32. Wikipedia micron = 10-6 meters The feature size of an integrated circuit is indicated by the width of a "wire," measured in microns (one micron is one millionth of a meter). Analysis and Design of Analog Integrated Circuits (4th Edition)