**Tom Kelliher, CS 240**

**Apr. 9, 2012**

Read 5-8.

Sequential circuit analysis.

- Sequential circuit design process.
- Unused states.
- Examples.

VHDL for sequential circuits.

- Obtain a state diagram. Assign binary numbers to the states (a
non-trivial problem, actually).
- Obtain a state table.
- Derive flip-flop input equations from the next state entries and
output equations. Simplify.
- Draw your schematic.

Suppose your design has 6 states:

- Two unused states.
- What happens if the circuit enters one of these states?

- Sequence recognizer for 010.
- Serial comparator. Inputs: A, B, msb. A and B are received least
significant bit first. Receipt of msb is co-incident with msb's of A and
B and resets circuit to begin next comparison. Output 0 if ,
otherwise 1.
- Serial comparator. Inputs: A, B, lsb. A and B are received most
significant bit first. Receipt of lsb is co-incident with lsb's of A and
B and resets circuit to begin next comparison. Output 0 if ,
otherwise 1.
- Given an unsigned binary value serially, starting from the lsb,
compute . Hint: How would you compute ?

Thomas P. Kelliher 2012-04-07 Tom Kelliher