Day 23: Mat385

Today:

• Reminder: exam 2 next time (chapters 3-6)
  • You may use one side of an 8.5x11 sheet (inches!)
  • Here are some old tests (these will generally contain bits of chapter 7):
    • 2006 Spring test 2 (2006 Spring test 2 key)
    • 2005 Spring test 2 (2005 Spring test 2 key)
    • 2003 Fall test 2 (2003 Fall test 2 key)
    • This was a one-hour exam (course took place 3 days per week): 2002 Fall test 2 (2002 Fall test 2 key)
    • 2002 Spring test 2 (2002 Spring test 2 key)

  • Overview of Chapters 3-6

• Return Homeworks 6.2/6.3/6.4

• Collect 6.4s (will be available tomorrow morning, posted on my door)

• Questions in preparation for the exam?

• Section 7.2 (pdf): Logic Networks

Links:

• Why carry-lookahead out-performs simple full adders:

  "The 4-bit adder we just created is called a ripple-carry adder. It gets that name because the carry bits "ripple" from one adder to the next. This implementation has the advantage of simplicity but the disadvantage of speed problems. In a real circuit, gates take time to switch states (the time is on the order of nanoseconds, but in high-speed computers nanoseconds matter). So 32-bit or 64-bit ripple-carry adders might take 100 to 200 nanoseconds to settle into their final sum because of carry ripple. For this reason, engineers have created more advanced adders called carry-lookahead adders. The number of gates required to implement carry-lookahead is large, but the settling time for the adder is much better."

• How electromagnets work
• How relays work