09 - 14-Sep-1011:31 AMMSI Elements1University of Florida,...

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Unformatted text preview: 14-Sep-1011:31 AMMSI Elements1University of Florida, EEL 3701 File 09 Drs. Schwartz & ArroyoEEL 3701EEL 3701Menu MSI elements>Decoders (pages 2-11)>Encoders (page 12)>Multiplexers (pages 15-17, 19-25)>DeMux (page 18)>Open collector gates (pages 25-32)Look into my ...1University of Florida, EEL 3701 File 09 Drs. Schwartz & Arroyo>Tri-state Buffers (pages 33-37)See Lam Figures from chapter 4EEL 3701EEL 37013-to-8 Decoder(3 input to 8 output; binary to singulary #)DecoderZA2Z1Look at Z= /A2/A1/ALook at Z1= /A2/A1AZ73-to-8 Decoder2A1AZ-Z71A2(H)A2(L)A2(L)Z (H2University of Florida, EEL 3701 File 09 Drs. Schwartz & ArroyoA1(H)A(H)Z(H)A1(L)A(L)A1(L)A(H)Z1(H)What is the equation of Z6? ____________Draw the circuit.14-Sep-1011:31 AMMSI Elements2University of Florida, EEL 3701 File 09 Drs. Schwartz & ArroyoEEL 3701EEL 3701Decoder A decoderis a circuit that performs the following Unit Vectors> If X1X=00, Z=1, Z1=Z2=Z3=0, i.e., Z3Z2Z1Z=0001 = ulogic:DecoderX1(H)X(H)Z(H)Z1(H)Z2(H)Z3(H)A1AYY1Y2Y33University of Florida, EEL 3701 File 09 Drs. Schwartz & Arroyo> If X1X=01, Z1=1, Z=Z2=Z3=0, i.e., Z3Z2Z1Z=0010 = u1> If X1X=10, Z2=1, Z=Z1=Z3=0, i.e., Z3Z2Z1Z=0100 = u2> If X1X=11, Z3=1, Z=Z1=Z2=0, i.e., Z3Z2Z1Z=1000 = u3EEL 3701EEL 3701Decoder with Enable A decoderwith an enable, E, performs the following logic>If E=1, then Zi=1 and all other Zs=0 One selectedfollowing logic:DecoderA1AEYY1Y2Y3X1(H)X(H)E(H)Z(H)Z1(H)Z2(H)Z3(H)4University of Florida, EEL 3701 File 09 Drs. Schwartz & Arroyo>If E=0, the all Zs=0 None selected>Thus, when E=1 and X1X=102=2, Z2=1, Z=Z1=Z3=0. >A decoder (when enabled) decodes a binary word In this example, a two bitbinary word 14-Sep-1011:31 AMMSI Elements3University of Florida, EEL 3701 File 09 Drs. Schwartz & ArroyoEEL 3701EEL 3701 Decoders are useful because Decoder: Why?DecoderA1AEYY1Y2Y3X1(H)X(H)E(H)Z(H)Z1(H)Z2(H)Z3(H)quite often information is encoded Why? What is an enable input? Why do we need it?>Added to: (1) Keep the circuit out of the way when not needed5University of Florida, EEL 3701 File 09 Drs. Schwartz & Arroyo (2) Because in a true singulary representation all zeros are not allowed. Thus, all zis 0 is not legal (by definition).>The IC works if Enable = 1, else chip is out of the circuit.EEL 3701EEL 3701Decoder Expansion Make a 3-to-8 decoder with two2 t4 ddX2(L)X2(H)Z(H)AYX1(H)3-to-8 DecoderZ(H)Z1(H)Z2(H)YY1Y2X2(H)A2-to-4 decoders2-to-4DecoderZ1(H)Z2(H)Z3(H)X2(L)A1AEY1Y2Y32-to-4DecoderX1(H)X(H)X2(H)A1AEYY1Y2YZ4(H)Z5(H)Z6(H)Z (H1X(H)X1(H)X(H)Z3(H)A1AY322Z4(H)Z5(H)Z6(H)Z7(H)Y4Y5Y6Y7 Can you do this and keep an enable on the new 3-to-8 decoder?Do itE(H)EFunctional Block Diagram6University of Florida, EEL 3701 File 09 Drs. Schwartz & ArroyoNOTE:We can build 3-to-8, 4-to-16, 5-to-32 decoders using 2-to-4s....
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This note was uploaded on 01/06/2011 for the course EEL 3701c taught by Professor Gugel during the Spring '05 term at University of Florida.

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09 - 14-Sep-1011:31 AMMSI Elements1University of Florida,...

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