Final answer:
To modify a 0-cold logic decoder to a 1-hot logic decoder, invert each output line using NOT gates, such that for any input, one output line is high and the rest are low.
Step-by-step explanation:
To modify a 0-cold logic decoder to operate like a 1-hot logic decoder, you would need to invert the output. Typically, a 0-cold logic decoder outputs a low signal (0) for the selected line and high signals (1) for all non-selected lines. To convert this into a 1-hot logic, where the selected line is high (1) and all others are low (0), you can use NOT gates (inverters) on each output of the original decoder.
For instance, suppose you have a 2-to-4 line decoder. The outputs without inversion are 0001, 0010, 0100, and 1000 for inputs 00, 01, 10, and 11 respectively (0-cold). To convert it to 1-hot logic, you would place an inverter after each output, changing the outputs to 1110, 1101, 1011, and 0111 respectively for the same set of inputs. This modification ensures that for any given input, exactly one output line is high (1), and the rest are low (0), which defines the 1-hot encoding scheme.