Marking of Mid-Term Exam

Question 1

• 2 marks for each of the first 3 expressions (total of 6)
• 1 mark for the last expression (tRHDZ = tZROS)
• 1 mark for each margin (total of 4)

Question 2

• 2 marks if all states transition to a single state (X) when ALE is high
• 2 marks if X transitions to Y if ALE low
• 2 marks if READY output for Y is low
• 2 marks if READY output for all other states were high
• 2 marks if Y transitions to Z if ALE low
• 2 marks if Z transitions to Z (and possibly up to 4 other states) when ALE is low

On your exam paper I've usually labeled the state your state machine enters when ALE is high as "x", the next state as "y" and sometimes the following state as "z". The READY output for state "y" has to be low, all others have to be high.

Question 3

• 2 marks for having 4 RAMS
• 2 marks for decoder input being A[14:23]
• 2 marks for 1 CS output per pair of RAMs
• 2 marks if RAM data inputs are D[0:7] and D[8:15]
• 2 marks if RAM address inputs are A[1:13]
• 2 marks if each pair of RAMs selected by each CS has D[0:7] and D[8:15]