3-10數(shù)據(jù)比較器電子課件教學(xué)版

第三章組合邏輯電路

3.2常用中規(guī)模集成組合邏輯電路

3.2.4數(shù)據(jù)比較器主講人：黃麗亞1.并行4位數(shù)據(jù)比較器7485圖3.2.33(b)簡(jiǎn)化符號(hào)A3～A0、B3

～B0

：數(shù)碼輸入端；(A>B)i(A=B)i(A<B)i：級(jí)聯(lián)輸入端；FA>B、FA=B、FA<B

：比較結(jié)果輸出端；表3.2.104位數(shù)據(jù)比較器7485功能表100???A0>B0A1=B1A2=B2A3=B30

1

0???A0<B0A1=B1A2=B2A3=B3010???????A2<B2A3=B3100???????A2>B2A3=B31

00?????A1>B1A2=B2A3=B301

0?????A1<B1A2=B2A3=B3A3<B3A3>B3A3B3????A2B2????A1B1????A0B00

10???100???FA>BFA<BFA=B(A>B)i(A<B)i(A=B)i輸出輸入續(xù)表000110A0=B0A1=B1A2=B2A3=B3110000A0=B0A1=B1A2=B2A3=B3001001A0=B0A1=B1A2=B2A3=B3001011A0=B0A1=B1A2=B2A3=B3001101A0=B0A1=B1A2=B2A3=B3A3=B3A3=B3A3=B3A3B3A2=B2A2=B2A2=B2A2B2A1=B1A1=B1A1=B1A1B1A0=B0A0=B0A0=B0A0B0001111010010100100FA>BFA<BFA=B(A>B)i(A<B)i(A=B)i輸出輸入禁止輸入(1)串聯(lián)方式2.數(shù)據(jù)比較器的擴(kuò)展圖3.2.34例如：7485實(shí)現(xiàn)8位并行數(shù)據(jù)比較器。A3A2A1A0A7A6A5A4B3B2B1B0B7B6B5B4FA>BFA=BFA<B001圖3.2.35(2)并聯(lián)方式例如：7485實(shí)現(xiàn)16位并行數(shù)據(jù)比較器。例：用一片7485實(shí)現(xiàn)兩個(gè)5位二進(jìn)制數(shù)A4A3A2A1A0和B4B3B2B1B0的比較。解：A0B0(A>B)i(A<B)i(A=B)i00011011關(guān)鍵在最低位的設(shè)計(jì)A4A3A2A1B4B3B2B1FA>BFA=BFA<B001010100001A0組合電路B0例：用一片7485實(shí)現(xiàn)兩個(gè)5位二進(jìn)制數(shù)A4A3A2A1A0和B4B3B2B1B0的比較。解：關(guān)鍵在最低位的設(shè)計(jì)A4A3A2A1B4B3B2B1FA>BFA=BFA<BA0組合電路B0例：用一片7485實(shí)現(xiàn)兩個(gè)5位二進(jìn)制數(shù)A4A3A2A1A0和B4B3B2B1B0的比較。A0B0(A>B)i(A<B)i(A=B)i00011011000110110000001001001011001101001111010010100100FA>BFA<BFA=B(A>B)i(A<B)i(A=B)iФФ1010100ФФ1(A>B)i=A0(A<B)i=B0(A=B)i=A0⊙B0A0B0(A>B)i(A<B)i(A=B)i00011011ФФ1010100ФФ1(A>B)i=A0(A