Logic Design CS221 1 st Term Storage (memory) Cairo University Faculty of Computers and Information
24/10/2009 cs221 – sherif khattab 2 Administrivia homework #3 due Dec. 8 th in lecture Project design due Dec. 8 th in lecture course web site:
24/10/2009 cs221 – sherif khattab 3 multiplexers with 3-state gates 3-state gates logic 0 logic 1 high-impedance (open) 3-state buffer gate
24/10/2009 cs221 – sherif khattab 4 multiplexers with 3-state gates
24/10/2009 cs221 – sherif khattab 5 multiplexers with 3-state gates
24/10/2009 cs221 – sherif khattab 6 storage elements storage (memory) elements store bits while power is on until input signals cause them to switch the stored bits stored n bits input signals
24/10/2009 cs221 – sherif khattab 7 storage elements latches: storage elements that operate on the levels of input signals (0 or 1) level-sensitive flip-flops: storage elements that operate on the transitions in input signals (0->1 or 1->0) edge-sensitive flip-flops are more common. flip-flops are constructed from latches.
24/10/2009 cs221 – sherif khattab 8 SR-latch 2 inputs: S (Set) and R (Reset) 2 outputs: Q and Q' Function Table
24/10/2009 cs221 – sherif khattab 9 SR-latch with enable
24/10/2009 cs221 – sherif khattab 10 D latch
24/10/2009 cs221 – sherif khattab 11 graphic symbols for latches
24/10/2009 cs221 – sherif khattab 12 D flip-flop edge-triggered
24/10/2009 cs221 – sherif khattab 13 D flip-flop