Faculty of Computers and Information Cairo University Faculty of Computers and Information Logic Design CS221 1st Term 2009-2010 Counters
Administrivia homework #4 due next lecture meeting with mentor TAs on wednesday المشروعات الصغيرة: الخميس ٩ص-٥م 24/10/2009 cs221 – sherif khattab
serial adder 24/10/2009 cs221 – sherif khattab
serial adder with JK flip-flop 24/10/2009 cs221 – sherif khattab
serial adder with JK flip-flop 24/10/2009 cs221 – sherif khattab
universal shift register 24/10/2009 cs221 – sherif khattab
universal shift register graphic symbol 24/10/2009 cs221 – sherif khattab
universal shift register function table 24/10/2009 cs221 – sherif khattab
binary counters an n-bit binary counter consists of n flip-flops and can count in binary from 0 through 2n - 1 Binary counters use flip-flops in complementing mode, such as: T flip-flop with T=1 JK flip-flop with J=K=1 D flip-flop with D=Q' 24/10/2009 cs221 – sherif khattab
ripple counters A0 is complemented every clock cycle A1: every time A0 goes from 1 to 0 (negative edge) A2: every time A1 goes from 1 to 0 (negative edge) 24/10/2009 cs221 – sherif khattab
binary ripple counter 24/10/2009 cs221 – sherif khattab
synchronous counters All flip-flops have a common clock 24/10/2009 cs221 – sherif khattab
carry propagation when is C4 ready? after 2 gates x 4 adders = 8 gate delays 24/10/2009 cs221 – sherif khattab
carry propagation in order for second adder to have its inputs ready quickly, can we compute C1 from A0 and B0 and C0? when is C1 = 1? when A0 and B0 = 1 OR (A0 NOT EQUAL B0 ) AND C0 = 1 Ci+1 = AiBi + (Ai XOR Bi) Ci 24/10/2009 cs221 – sherif khattab
carry propagation 24/10/2009 cs221 – sherif khattab