8-Line to 3-Line Priority Encoder truth table:
Inputs | Outputs
EI | 0 1 2 3 4 5 6 7 | A2 A1 A0 | GS EO
---|-----------------|----------|-------
1 | X X X X X X X X | 1 1 1 | 1 1
0 | 1 1 1 1 1 1 1 1 | 1 1 1 | 1 0
0 | X X X X X X X 0 | 0 0 0 | 0 1
0 | X X X X X X 0 1 | 0 0 1 | 0 1
0 | X X X X X 0 1 1 | 0 1 0 | 0 1
0 | X X X X 0 1 1 1 | 0 1 1 | 0 1
0 | X X X 0 1 1 1 1 | 1 0 0 | 0 1
0 | X X 0 1 1 1 1 1 | 1 0 1 | 0 1
0 | X 0 1 1 1 1 1 1 | 1 1 0 | 0 1
0 | 0 1 1 1 1 1 1 1 | 1 1 1 | 0 1
74ls148优先编码器,其功能表如上,两个148就可以级连成16-4的编码器了.
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3-to-8 decoder/demultiplexer truth table:
__ __ | Select |
GL G1 G2 | C B A | Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
-----------|---------|-------------------------------
X X 1 | X X X | 1 1 1 1 1 1 1 1
X 0 X | X X X | 1 1 1 1 1 1 1 1
-----------|---------|-------------------------------
0 1 0 | 0 0 0 | 0 1 1 1 1 1 1 1
0 1 0 | 0 0 1 | 1 0 1 1 1 1 1 1
0 1 0 | 0 1 0 | 1 1 0 1 1 1 1 1
0 1 0 | 0 1 1 | 1 1 1 0 1 1 1 1
-----------|---------|------------------------------
0 1 0 | 1 0 0 | 1 1 1 1 0 1 1 1
0 1 0 | 1 0 1 | 1 1 1 1 1 0 1 1
0 1 0 | 1 1 0 | 1 1 1 1 1 1 0 1
0 1 0 | 1 1 1 | 1 1 1 1 1 1 1 0
-----------|---------|------------------------------
1 1 0 | X X X | Output corresponding to stored
| | address 0; all others 1
138是3-8译码器,功能表如上.
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