I am thinking about designing a logic circuit to perform like an automatic response feedback system. Basically, I will be using a keypad for user entry for an option from (a,b,c, or d) choices. I will use 4 7-segment displays to show the count(frequency) of each option based on all user entries to show the results. I wanted to know how to store the previous "count" of each option(a,b,c,d) before the next user enters an option so that the display always shows the current total results?... would I need to use sequential design for this to store updated count?

Please give me an idea how to approach this design problem, perhaps with a schematics sketch?

Thanks

 

This sounds like a job for a microcontroller. I think it would be too complex to do it with logic chips. Especially making sure noone presses 2 buttons.

 

A switch type joystick might be superior for the input. You do not have to look to make the motion like you do to see which key to press. Or you could make a diamond layout for four pushbuttons.

 

Another convenience to the design would be to make it wireless. Each voting unit would have a unique address. The base unit would transmit an address of the unit it was polling and only the voting unit that recognized the address would respond back with its selection.

hgmjr