计算机系统讲座s.pdf

Overview

Overview

•Selectorcircuit

•Multiplexer

•Two-linedecoder

•Dataselectorwithtwo-linedecoder

•Implementingafunctionwithlogicgates

2

2

Selectorcircuit

Selectorcircuit

•Thiscircuitimplements

V

thefunction:

–Y=not(VandW),

where,

–V=not(AandS),

Z

–W=not(ZandB),

W–Z=not(SandS)

=notS.

•Combiningaltogetherweget:

Y=not(not(AandS)andnot(not(S)andB)).

3

3

Truthtableforselectorcircuit

Truthtableforselectorcircuit

4

4

Selectorfunction

Selectorfunction

•Onemaygiveashortdefinitionofthe

functionfromthetruthtable:

OrY=(SA)V(-SB)

5

5

Ex.Reimplementtheselectorcircuit

Ex.Reimplementtheselectorcircuit

usingAND,OR,NOTgates

usingAND,OR,NOTgates

6

6

Dataselector,ormultiplex