Yes i agree software would be easier, but i have just started doing a 3 month internship at an electronics company and I was asked to develop this circuit.
They cannot use reporgrammable logic devices (somehting to do with insurance and approvals)
The invertor on output is connected to aynchronous clear input, so you will get a short impulse on output as input signal goes high... It will look something like this:
Thanks for the advice but the difficulty in this matter is that I need to determine which of the three signals was set high last?
.......... ____________
in1___|
..............____________
in2_____|
.....................____________
in3_______|
Thus i need a means of knowing input 3 was set high last?
there are rc filters to detect a rising edge for each input, and the sr flip-flop remembers which input was last pressed. there are 3 outputs, each one indicates which was last pressed.