Path: utzoo!utgpu!news-server.csri.toronto.edu!mailrus!ames!haven!adm!cmcl2!dasys1!aj-mberg From: aj-mberg@dasys1.uucp (Micha Berger) Newsgroups: comp.arch Subject: Re: Back to Basics, Which Flip Flop Do you use ? Summary: Flip-flop primer Keywords: D, T, JK, SR Message-ID: <1990May4.144518.2898@dasys1.uucp> Date: 4 May 90 14:45:18 GMT References: <847@berlioz.nsc.com> <369@newave.UUCP> <7253@ucdavis.ucdavis.edu> Sender: aj-mberg@dasys1.UUCP (Micha Berger at AishDas Society) Reply-To: mberger1%tasha@graf.poly.edu (Micha Berger at EveryWare PC Systems) Organization: AishDas Society: 73-32 173 St, Hillcrest NY 11366, (718) 380-7572 Lines: 39 There are several types of flip-flop. Let's list them once, and clear the whole thing up. RS flip flop: JK flip flop: Inputs Outputs Inputs Outputs R S Q Q' J K Q Q' -------------------- -------------------- 0 0 q q' No Change 0 0 q q' No Change 0 1 1 0 Set 0 1 0 1 Set 1 0 0 1 Reset 1 0 1 0 Reset 1 1 - - Not Stable 1 1 q' q Toggle Input Outputs Input Outputs D Q Q' T Q Q' -------------------- -------------------- 0 0 1 Reset 0 q q' No Change 1 1 0 Set 1 q' q Toggle JK gives you the most control, but if you know that 1 1 won't come up, RS is cheaper. D is good for memory, and T is good for counters, and other applications where the "Toggle" description is simpler. In addition: latch: no clock (there can be no T or JK latches) flip-flop: clocked transparent: can change any time while the clock is active (also can't be T or JK) edge-triggered: change comes shortly after clock edge, based on input a short time before the clock edge. leading edge: relevent edge is 0-1 transition trailing edge: relevent edge is 1-0 transition -- Micha Berger mberger1%tasha@graf.poly.edu If nothing you try will work, try to fail.