1. ECE 206 - Fall 2000 - G. Byrd1 Register A register stores a multi-bit value. We use a collection of D-latches, all controlled by a common WE. When WE=1, n-bit value D is written to register.

2. ECE 206 - Fall 2000 - G. Byrd2 Memory Now that we know how to store bits, we can build a memory – a logical k × m array of stored bits. k = 2 n locations m bits Address Space: number of locations (usually a power of 2) Addressability: number of bits per location (e.g., byte-addressable)

3. ECE 206 - Fall 2000 - G. Byrd3 2 2 x 3 Memory address decoder word select word WE address write enable input bits output bits Address 11--> Address 10--> Address 01--> Address 00 | | v

4. ECE 206 - Fall 2000 - G. Byrd4 Clock Simply oscillates between high and low signal. You need a clock for your D-flip flop. http://www.ee.nthu.edu.tw/jcliao/Logic98/chap06/P212.JPG

5. ECE 206 - Fall 2000 - G. Byrd5 Remember the Combined Requirements (3 pts) Reset signal works as intended (3 pts) Design is organized on multiple pages (9 pts) Ability to store ALU result into memory

6. ECE 206 - Fall 2000 - G. Byrd6 Clues - Use the pictures in the book P.70/P.69 - What is required for you to be Able to write to a register? 1. Which Address 2. Write Enable ON 3. Write Switch ON 4. Clock pressed - You will need muxes in order to read from memory and be able to display out, this part is tricky.

7. ECE 206 - Fall 2000 - G. Byrd7 LC-3 Data Path Combinational Logic State Machine Storage