Q: Huh?

A: You have to design a controller for a 7 segment display. The controller is a box that implements 7 boolean functions (one for each of the segments). Here is a picture:

There are a bunch of gates inside the controller - the gates are connected so that if the input is all 0s, the controller will turn on all the outputs except X1 - this results in a display of the digit '0'. You have to come up with the gates that make this happen. Your controller must also work for all the possible patterns of inputs (not just when they are all 0s) - a complete list of the all the patterns and the resulting display is shown in the homework assignment.

Q: How do I get started? I don't understand how I can have 7 different outputs!

A: You can treat each output (The Xs) as a Boolean function. Just take one at a time and go through the steps we used in class to design the decoder and multiplexor. Start by constructing a truth table, then convert this to POS or SOP expressions, and then draw the corresponding logic diagram. You don't have to use SOP or POS forms for the Boolean expressions, this is just a suggestion to help you get started.

Note that if you do go for SOP form, there is lots of minimization that can be done. You are not required to do any minimization, but it will help make your drawing smaller...