Some Basic Terms

• We tend to measure things in powers of two
• Hopefully you can answer why now, but surely at the end of the semester
• Memorize powers of two up to 2¹⁰, 1024
• In our world
  • 1K = 10³ or sometimes 2¹⁰ (Kilo)
  • 1M = 10⁶ or sometimes 2²⁰ (Mega)
  • 1G = 10⁹ or sometimes 2³⁰ (Giga)
  • 1T = 10¹² or sometimes 2⁴⁰ (Tera)
  • 1P = 10¹⁵ or sometimes 2⁵⁰ (Peta)
• Time is measured as
  • 1 second = 10^-3ms (millisecond)
  • 1 second = 10^-6us (microsecond)
  • 1 second = 10^-9ns (nanosecond)
  • 1 second = 10^-12ps (picosecond)
  • 1 second = 10^-15fs (femtosecond)
• Clocks operate by generating a regular pulse
  • 
  • We describe a clock by it's frequency
  • Or how many cycles it goes through in a second.
  • The unit of measure is a Hertz (Hz)
    • 1 Hz = 1 cycle/second
    • 1 KHz = 1x10³cycles/second
    • 1 GHz = 1x10⁹cycles/second
  • The period of a clock is how long a cycle lasts
    • Measured in seconds/cycle
    • A 20MHz clock has a period of
    • 1 second/1x10⁶ cycles
    • But we usually express this in ns/cycle
    • 1 sec/20x10⁶ cycles * 1x10⁹ns/sec
    • 1x10²ns/2 cycles = 50 ns/ cycle
  • The number of instructions a computer can execute in a second is related to it's clock speed.
    • But this is not necessarily a good way to determine performance
    • We will discuss this later.
  • We sometimes discuss computer performance in terms of mips
    • Millions of Instructions Per Second
    • This is probably a bad measurement, we will discuss this later
    • But it is useful for our purposes now.
• A bus is a collection of wires going the same place.
  • Generally it is used to carry data
  • For example from memory to the cpu
  • Busses are usually controlled by a clock
  • And thus have an associated frequency
• Memory is a collection of boxes to hold data
  • It is much slower than the cpu
  • And there is the bus too
  • Memory performance is often improved by cache
    • This is a much smaller chunk of memory much closer to the cpu
    • Dcache, Icache, L1, L2, L3 ...
    • Much more on this later
• There are a many more terms
  • Expansion slot names
  • Monitor and graphics system information
  • You should read this section carefully.
• This is just a quick pass, sort of to get you interested
• We will discuss many of these issues in greater detail as the semester goes along.

Standards Organizations

• A number of organizations set standards for hardware industry
  • IEEE - Institute of Electrical and Electronic Engineers
    • How we represent floating point numbers
  • ITU - International Telecommunications Union
  • ANSI - American National Standards Institute
  • ISO - International Organization for Standardization