**Tom Kelliher, CS 240**

**Feb. 3, 2012**

Collect homework assignments.

Read 2.9, 6.1-6.2.

New homework assignment.

Simplifying K-maps.

- NAND gates.
- Two-level physical realizations.
- Parity generation and checking.
- BCD to 7-segment decoder example.

Circuit technologies.

- Not AND. Symbol. Truth table.
- At the physical level, this is what we work with.
- Completeness: Given a two-input NAND show how to implement inverter,
AND, OR.
- NOR completely analogous.

Given that we only have NAND gates, implement: . (Draw using AND and OR, derive NAND implementation, and draw.)

- EXOR symbol, truth table.
- EXOR = odd function. (NEXOR = even)
- A ``big'' EXOR can be recursively constructed from ``small'' EXORs.
- Parity generate and check circuit for ASCII data:
Show a few examples.

Simplify and implement .

Thomas P. Kelliher 2012-02-01 Tom Kelliher