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Hardware Outline

Hardware Outline. Secondary Storage Media Types Speed, Price, Size CD-ROM & DVD-ROM CD-ROM & DVD-ROM: Disadvantage CD-ROM & DVD-ROM: Advantages Why Are Floppies So Expensive Per MB? I/O I/O: Input Devices I/O: Output Devices Bits Bytes Words Putting Bits Together

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Hardware Outline

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  1. Hardware Outline • Secondary Storage • Media Types • Speed, Price, Size • CD-ROM & DVD-ROM • CD-ROM & DVD-ROM: Disadvantage • CD-ROM & DVD-ROM: Advantages • Why Are Floppies So Expensive Per MB? • I/O • I/O: Input Devices • I/O: Output Devices • Bits • Bytes • Words • Putting Bits Together • Putting Bits Together (cont’d) • Powers of 2 • Powers of 2 vs Powers of 10 • KB, MB, GB, TB, PB • Kilo, Mega, Giga, Tera, Peta • Moore’s Law • Implication of Moore’s Law • Double, double, … • Hardware Outline • What is a Computer? • Components of a Computer • Categories of Computer Hardware • Central Processing Unit (CPU) • CPU Examples • CPU Parts • CPU: Control Unit • CPU: Arithmetic/Logic Unit • CPU: Registers • How Registers Are Used • Storage • Primary Storage • Cache • From Cache to the CPU • Main Memory (RAM) • Main Memory Layout • RAM vs ROM • Speed => Price => Size • How Data Travel Between RAM and CPU • Loading Data from RAM into the CPU • RAM is Slow • Why Have Cache? CS1313: Hardware Lesson Fall 2005

  2. What is a Computer? “… [A] programmable electronic device that can store, retrieve and process data.” (N. Dale & D. Orshalick, Introduction to PASCAL and Structured Design, D.C. Heath & Co., Lexington MA, 1983, p. 2) CS1313: Hardware Lesson Fall 2005

  3. Components of a Computer Computer Hardware Physical Devices Software Instructions & Data DON’T PANIC! This discussion may be confusing at the moment; it’ll make more sense after you’ve written a few programs. CS1313: Hardware Lesson Fall 2005

  4. Categories of Computer Hardware • Central Processing Unit (CPU) • Storage • Primary: Cache, RAM • Secondary: Hard disk, removable (e.g., CD) • I/O • Input Devices • Output Devices CS1313: Hardware Lesson Fall 2005

  5. Central Processing Unit (CPU) The Central Processing Unit(CPU), also called the processor, is the “brain” of the computer. Intel PentiumD Smithfield Dual Core Innards http://www6.tomshardware.com/cpu/20050405/pentium_d-02.html Intel PentiumD (exterior) http://www6.tomshardware.com/cpu/20050405/ CS1313: Hardware Lesson Fall 2005

  6. CPU Examples • Intel Pentium 4/AMD Athlon XP (Windows PCs) • Motorola PowerPC G5 (Apple Macintoshes) • Intel Itanium2 (servers) CS1313: Hardware Lesson Fall 2005

  7. CPU Parts The CPU consists of three main parts: • Control Unit • Arithmetic/Logic Unit • Registers Registers Control Unit Arithmetic/Logic Unit Fetch Next Instruction Add Sub Integer Fetch Data Store Data Mult Div Increment Instruction Ptr Floating Point And Or Execute Instruction … Not … CS1313: Hardware Lesson Fall 2005

  8. CPU: Control Unit The Control Unitdecides what to do next. For example: • memory operations: e.g., load data from main memory (RAM) into the registers, or store data from the registers into main memory; • arithmetic/logical operations: e.g., add, multiply; • branch: choose among several possible courses of action. CS1313: Hardware Lesson Fall 2005

  9. CPU: Arithmetic/Logic Unit The Arithmetic/Logic Unit(ALU) performs arithmetic and logical operations. • Arithmetic operations: e.g., add, subtract, multiply, divide, square root, cosine, etc. • Logical operations: e.g., compare two numbers to see which is greater, check whether a true-false statement is true, etc. CS1313: Hardware Lesson Fall 2005

  10. CPU: Registers Registersare memory-like locations inside the CPU where data reside that are being used right now. That is, registers hold the operands being used by the current arithmetic or logical operation, or the result of the arithmetic or logical operation that was just performed. For example, if the CPU is adding two numbers, then the addend is in some register, the augend is in another register, and after the addition, the sum is in yet another register. A typical CPU has only a few hundred to a few thousand bytes of registers. CS1313: Hardware Lesson Fall 2005

  11. How Registers Are Used • Every arithmetic or logical operation has one or more operands and one result. • Operands are contained in source registers. • A “black box” of circuits performs the operation. • The result goes into a destination register. operand Register Ri result Register Rk operand Register Rj Operation circuitry addend in R0 5 ADD Example: 12 sum in R2 7 augend in R1 CS1313: Hardware Lesson Fall 2005

  12. Storage There are two major categories of storage: • Primary • Cache • Main memory (RAM) • Secondary • Hard disk • Removable (e.g., CD, floppy) CS1313: Hardware Lesson Fall 2005

  13. Primary Storage Primary storageis where data and instructions reside when they’re being used by a program that is currently running. • Typically is volatile: The data disappear when the power is turned off. • Typically comes in two subcategories: • Cache • Main memory (RAM) CS1313: Hardware Lesson Fall 2005

  14. Cache Cachememory is where data and instructions reside when they are going to be used very very soon. • Very fast(typically 50% - 100% of the speed of the registers). • Therefore, very expensive (e.g., $700 per MB) http://www.pricewatch.com/ • Therefore, very small (e.g., 1/8 to 2 MB) … but still much bigger than registers. CS1313: Hardware Lesson Fall 2005

  15. From Cache to the CPU CPU 67 GB/sec on a 1.5 GHz Pentium4 48 GB/sec (72%) on a 1.5 GHz Pentium4 Cache Typically, data move between cache and the CPU at speeds comparable to that of the CPU performing calculations. CS1313: Hardware Lesson Fall 2005

  16. Main Memory (RAM) Main memory(RAM) is where data and instructions reside when a program that is currently running is going to use them at some point during the run (whether soon or not). • Much slower than cache (e.g., about 1-10% of CPU speed for RAM, vs 50-100% of CPU speed for cache) • Therefore, much cheaper than cache (e.g., $0.08/MB for RAM vs $700/MB for cache) • Therefore, much larger than cache (e.g., 64 to 2,048 MB for RAM vs 1/8 to 2 MB for cache) CS1313: Hardware Lesson Fall 2005

  17. Main Memory Layout Main memory is made up of locations, also known as cells. Each location has a unique integer address that never changes. Each location has a value – also known as the contents – that the CPU can look at and change. We can think of memory as one contiguous line of cells. CS1313: Hardware Lesson Fall 2005

  18. RAM vs ROM RAM: Random Access Memory • Memory that the CPU can look at and change arbitrarily (i.e., can load from or store into any location at any time, not just in a sequence). • We often use the phrases Main Memory, Memory and RAM interchangeably. • Sometimes known as core, named for an older memory technology. ROM: Read Only Memory • Memory that the CPU can look at arbitrarily, but cannot change. CS1313: Hardware Lesson Fall 2005

  19. Speed => Price => Size • Registers are VERY fast, because they are etched directly into the CPU. • Cache is also very fast, because it’s also etched into the CPU, but it isn’t directly connected to the Control Unit or Arithmetic/Logic Unit. Cache operates at speeds similar to registers, but cache is MUCH bigger than the collection of registers (typically on the order of 1,000 times as big). • Main memory (RAM) is much slower than cache, because it isn’t part of the CPU, and therefore it’s much cheaper than cache, and therefore it’s much bigger than cache (e.g., 1,000 times as big). CS1313: Hardware Lesson Fall 2005

  20. How Data Travel Between RAM and CPU The bus is the connection from the CPU to main memory; all data travel along it. CPU For now, we can think of the bus as a big wire connecting them. CS1313: Hardware Lesson Fall 2005

  21. Loading Data from RAM into the CPU CS1313: Hardware Lesson Fall 2005

  22. RAM is Slow The speed of data transfer between Main Memory and the CPU is much slower than the speed of calculating, so the CPU spends most of its time waiting for data to come in or go out. CPU 67 GB/sec on a 1.5 GHz Pentium4 Richard Gerber, The Software Optimization Cookbook: High-performance Recipes for the Intel Architecture. Intel Press, 2002, pp. 161-168. Bottleneck 3.2 GB/sec (5%) ftp://download.intel.com/design/Pentium4/papers/24943801.pdf CS1313: Hardware Lesson Fall 2005

  23. Why Have Cache? Cache is nearly the same speed as the CPU, so the CPU doesn’t have to wait nearly as long for stuff that’s already in cache: it can do more operations per second! CPU 67 GB/sec on a 1.5 GHz Pentium4 48 GB/sec (72%) http://www.anandtech.com/showdoc.html?i=1460&p=2 3.2 GB/sec (5%) CS1313: Hardware Lesson Fall 2005

  24. Secondary Storage • Nonvolatile: data don’t disappear when power is turned off. • Much slower than RAM, therefore much cheaper, therefore much larger. • Other than hard disk, most are portable: they can be easily removed from your computer and taken to someone else’s. CS1313: Hardware Lesson Fall 2005

  25. Media Types • Magnetic: • Always can be read • Always can be written and rewritten multiple times • Contents degrade relatively rapidly over time • Can be erased by magnets • Optical • Always can be read • Some can be written only once, some can be rewritten multiple times • Contents degrade more slowly than magnetic media • Can’t be erased by magnets • Paper: forget about it! CS1313: Hardware Lesson Fall 2005

  26. Speed, Price, Size * Maximum among models commonly available for PCs Note: all numbers are approximate as of Aug 2005 (bestbuy.com, buy.com, cendyne.com, creativelabs.com, dell.com, pricewatch.com, storagetek.com, toshiba.com). CS1313: Hardware Lesson Fall 2005

  27. CD-ROM & DVD-ROM When a CD or DVD holds data instead of music or a movie, it acts very much like Read Only Memory (ROM): • it can only be read from, but not written to; • it’s nonvolatile; • it can be addressed essentially arbitrarily (it’s not actually arbitrary, but it’s fast enough that it might as well be). CS1313: Hardware Lesson Fall 2005

  28. CD-ROM & DVD-ROM: Disadvantage Disadvantage of CD-ROM/DVD-ROM compared to ROM: • CD-ROM and DVD-ROM are much slowerthan ROM. • CD-ROM is 7.8 MB/sec (peak); DVD-ROM is 16 MB/sec. • Most ROM these days is 6,554 MB/sec (roughly 400 times as fast as DVD and 800 times as fast as CD). CS1313: Hardware Lesson Fall 2005

  29. CD-ROM & DVD-ROM: Advantages Advantages of CD-ROM/DVD-ROM compared to ROM: • CD-ROM and DVD-ROM are much cheaperthan ROM. • Blank CDs and blank DVDs are less than $0.0005/MB. • ROM is even more expensive than RAM (which is $0.08/MB), because it has to be made special. • CD-ROM and DVD-ROM are much larger – they can have arbitrary amount of storage (on many CDs or DVDs); ROM is limited to a few GB. CS1313: Hardware Lesson Fall 2005

  30. Why Are Floppies So Expensive Per MB? CD-RWs cost less than $0.0005 per MB, but floppy disks cost about $0.35 per MB. Why? Well, an individual CD has much greater capacity than an individual floppy (700 MB vs. 1.44 MB), and the costs of manufacturing the actual physical objects are similar. So, the cost of a floppy per MBis much higher. CS1313: Hardware Lesson Fall 2005

  31. I/O We often say I/Oas a shorthand for “Input/Output.” CS1313: Hardware Lesson Fall 2005

  32. I/O: Input Devices We often say I/Oas a shorthand for “Input/Output.” Input Devicestransfer data into computer (e.g., from a user into memory). For example: • Keyboard • Mouse • Scanner • Microphone • Touchpad • Joystick CS1313: Hardware Lesson Fall 2005

  33. I/O: Output Devices We often say I/Oas a shorthand for “Input/Output.” Output Devicestransfer data out of computer (e.g., from memory to a user). For example: • Monitor • Printer • Speakers CS1313: Hardware Lesson Fall 2005

  34. Bits Bit(Binary digIT) • Tiniest possible piece of memory. • Made of teeny tiny transistors wired together. • Has 2 possible values that we can think of in several ways: • Low or High: Voltage into transistor • Off or On: Conceptual description of transistor state • False or True: Boolean value for symbolic logic • 0 or 1: Integer value • Bits aren’t individually addressable: the CPU can’t load from or store into an individual bit of memory. CS1313: Hardware Lesson Fall 2005

  35. Bytes Byte: a sequence of 8 contiguous bits (typically) • On most platforms(kinds of computers), it’s the smallest addressable piece of memory: typically, the CPU can load from or store into an individual byte. • Possible integer values: 0..255 or -128..127 (to be explained later) • Can also represent a character (e.g., letter, digit, punctuation; to be explained later) CS1313: Hardware Lesson Fall 2005

  36. Words Word: a sequence of 4 or 8 contiguous bytes (typically); i.e., 32 or 64 contiguous bits • On a few platforms (e.g., Cray J90), the smallest possible addressable piece of memory • Standard size for storing a number (integer or real) • Standard size for storing an address (special kind of integer) CS1313: Hardware Lesson Fall 2005

  37. Putting Bits Together 1 bit: 21 = 2 possible values: or 2 bits: 22 = 4 possible values 3 bits: 23 = 8 possible values 0 1 0 0 0 1 1 0 1 1 0 0 0 0 0 1 0 1 0 0 1 1 1 0 0 1 0 1 1 1 0 1 1 1 CS1313: Hardware Lesson Fall 2005

  38. Putting Bits Together (cont’d) 4 bits: 24 = 16 possible values … 8 bits: 28 = 256 possible values … 10 bits: 210 = 1,024 possible values … 16 bits: 216 = 65,536 possible values … 32 bits: 232 = 4,294,967,296 possible values (typical size of an integer in most computers today) CS1313: Hardware Lesson Fall 2005

  39. Powers of 2 (about a million) CS1313: Hardware Lesson Fall 2005

  40. Powers of 2 vs Powers of 10 A rule of thumb for comparing powers of 2 to powers of 10: 210~ 103 So: • 210~ 1,000 (thousand) • 220~ 1,000,000 (million) • 230~ 1,000,000,000 (billion) • 240~ 1,000,000,000,000 (trillion) • 250~ 1,000,000,000,000,000 (quadrillion) CS1313: Hardware Lesson Fall 2005

  41. KB, MB, GB, TB, PB Kilobyte(KB): 210 bytes, which is approximately 1,000 bytes (thousand) Megabyte (MB): 220 bytes, which is approximately 1,000,000 bytes (million) Gigabyte (GB): 230 bytes, which is approximately 1,000,000,000 bytes (billion) Terabyte (TB): 240 bytes, which is approximately 1,000,000,000 bytes (trillion) Petabyte (PB): 250 bytes, which is approximately 1,000,000,000,000,000 bytes (quadrillion) CS1313: Hardware Lesson Fall 2005

  42. Kilo, Mega, Giga, Tera, Peta CS1313: Hardware Lesson Fall 2005

  43. Moore’s Law Moore’s Law: Computing speed and capacity double every 18 to 24 months. In 1965 Gordon Moore (Chairman Emeritus, Intel Corp) observed the “doubling of transistor density on a manufactured die every year.” People have noticed that computing speed and capacity are roughly proportional to transistor density. Moore’s Law is usually hedged by saying that computing speed doubles every 18-24 months (typically 18). See: http://www.intel.com/research/silicon/mooreslaw.htm http://www.intel.com/pressroom/kits/quickreffam.htm CS1313: Hardware Lesson Fall 2005

  44. Implication of Moore’s Law If computing speed and capacity double every 18 months, what are the implications in our lives? Well, the average undergrad student is – to one significant figure – about 20 years old. And the average lifespan in the US – to one significant figure – is about 80 years. So, the average undergrad student has 60 years to go. So how much will computing speed and capacity increase during the time you have left? CS1313: Hardware Lesson Fall 2005

  45. Double, double, … 60 years / 18 months = 40 doublings What is 240? Consider the computer on your desktop today, compared to the computer on your desktop the day you die. How much faster will it be? Can we possibly predict what the future of computing will enable us to do? CS1313: Hardware Lesson Fall 2005

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