| (a) |
How many outputs does an encoder with 4 inputs have?
|
[1] |
| (b) |
Explain the difference between an ordinary encoder and a priority encoder.
|
[2] |
| (c) |
Design a circuit implementing a 4-input encoder, using AND, OR and NOT gates as required.
|
[3] |
| (d) |
Design a circuit implementing a 4-input priority encoder, using AND, OR and NOT gates as required.
|
[3] |
| (e) |
Suppose you need a priority encoder, but have only an ordinary encoder and a collection of logic gates. (i) Explain briefly how to construct an n-input priority encoder from an n-input ordinary encoder. [1 mark] (ii) Complete the following truth table,
showing how to turn the inputs for a 4-input priority encoder into
the inputs for a 4-input ordinary encoder.(
(iii) Complete the following circuit, so that it behaves like a 4-input priority encoder.
|
[6] |
are the highest-priority inputs.)[2 marks]
[3 marks]