π Encoder Β· Decoder Β· Multiplexer
select = 2
2-to-4 decoder
Turns a 2-bit binary number into βone of fourβ: exactly one output line lights up β the one whose number you entered. Built from 2 NOT and 4 AND gates.
| A1 | A0 | D0 | D1 | D2 | D3 |
|---|---|---|---|---|---|
| 0 | 0 | 1 | 0 | 0 | 0 |
| 0 | 1 | 0 | 1 | 0 | 0 |
| 1 | 0 | 0 | 0 | 1 | 0 |
| 1 | 1 | 0 | 0 | 0 | 1 |
- Memory chips: the address decoder picks exactly one row of memory cells to read or write
- Calculator & digital-clock displays: a BCD-to-7-segment decoder lights the right bars for each digit
- CPUs decode each instructionβs bits to switch on the right circuit (add, load, jumpβ¦)
- Lift (elevator) floor indicators