1. Sequential Logic

2. Logic Styles Combinational circuits – Output determined solely by inputs – Can draw solely with left-to-right signal paths

3. Logic Styles Sequential circuits – Output determined by inputs AND previous outputs – Feedback loop

4. AB Circuit If A = 1 output must be 1 ABO 00 01 101 111

5. AB Circuit If A = 0 and B = 1 output must be 0 ABO 00 010 101 111

6. AB Circuit If A = 0 and B = 0 output may be 1 or 0 ABO 000/1?? 010 101 111

7. AB Circuit Need to consider hidden input: ABLast Out Out 0000 0011 01x0 10x1 11x1

8. AB Circuit Describe next output O t+1 in terms of current output O t ABO t+1 00OtOt 010 101 111

9. Clocks Crystal Oscillators – Vibrate at known frequency when current applied – Used to generate clock signal:

10. Logisim Clock Clock alternates between high and low Button makes a nice manual clock

11. Hertz Frequency inverse of cycle time – Expressed in hertz. 1 Hz = 1 cycle per second 1 kilohertz (kHz) 1000 cycles/sec 1 megahertz (MHz) 1 million cycles/sec 1 gigahertz (GHz) 1 billion cycles/sec

12. Clocks Timing can be – Level-triggered : change can happen when clock high – Edge-triggered : change can happen on edge

13. Latches Latch : Level triggered memory

14. Flip Flops Flip Flop : edge triggered memory – Logisim won't reproduce

15. SR Circuit Set Reset circuit SRQ t+1 00QtQt 010 101 11 undefined

16. Logisim To simulate SR need to add noise to delays

17. Logisim Oscillation : Circuit trapped in flip/flop – need to restart

18. Clocked SR Latch Level triggered based SR circuit SRQ t+1 00QtQt 010 101 11 undefined

19. Clocked JK Latch JK makes SR safe – Prevent 1/1 from getting to SR - flips SRQ t+1 00QtQt 010 101 11

20. D Latch D Latch : Stores single bit during low clock DQ t+1 00 11

21. Memory's Atom Basic building block of memory

22. Logisim Built in D Flipflop – D – Clock – Preset (force 1) – Clear (force 0) – Enable (1 or floating is on)

23. Registers Register : Array of D Flip-flops

24. Registers Register : Write requires clock and write signal

25. Main Memory Big old matrix of flip flops

26. Main Memory 2-4 decoder logic picks memory address

27. Main Memory 3 bits wide

28. Implemeneted