Marking of Final Exam

• Question 1
  • 1 for syntax
  • 2 for local signal declarations (count, nextcount) of an allowable type
  • 1 for correct count size (>= 9 bits)
  • 1 for count reset (0/300) when switch is on
  • 1 for count held at final value (300/0) or additional state machine controls output when switch off
  • 1 for count change (increment/decrement)
  • 1 for setting 'light' signal output
  • 1 for process and if-statement syntax
  • 1 for counter signal assignment
• Question 2
  • 1 call getch
  • 1 compare to LF characters (0AH)
  • 2 range-check (30H to 39H)
  • 1 store in buffer (indirect addressing)
  • 1 increment count and/or pointer
  • 1 loop back
  • 1 put count in AX before returning
  • 1 register push/pop or saving
  • 1 RETurn instruction
• Question 3
  • 1 for each correct equation (no marks if answer not given as tnnn)
  • 1 if the equation is correct and the margin and Met (Y/N)? answer are both correct
  • no marks if tAW is t120+t123+t125 (not simplest equation or largest margin)
• Question 4
  • (a)
    • 1 for 2 banks of 2 chips
    • 1 if have A0-A12 going to the chips
    • 1 if show D0-D3 to one chip in a bank and D4-D7 to another
    • 1 if have common chip select to both chips in a bank
  • (b)
    • 1/2 for VHDL syntax
    • 1/2 for active-low outputs
    • 1/2 for address range = A15 to A13
    • 1/2 for correct constant value in comparison
• Question 5
  • (a)
    • 1 per right answer
  • (b)
    • 1 for right segment and offset values
    • 1 for right physical address
  • (c)
    • 1 for character value
    • 1 for baud rate
    • 1 if either of the above are correct