How to set initial state of 4 bit "exclusive output" Latch?
This is how everyone's specs ( or question) should be written as follows:

A Hierarchical Input Process Output or HIPO descrption. Same for documenting software routines. INs OUTs and FUNCTIONS


Inputs: 4 momentary SET switches (normally=0)
Process: Each switch acts as a SET to it's own Register AND a RESET to all others, thus creating an exclusive N bit SET function to Register


This is an async. latch function, not a edge-triggered synchronous type.
Initial Condition options; 1000, 0100, 0010, 0001, or 1111.  illegal=0000.


IN=0000 does not converge to steady state

OUTPUT Latch follows INPUT exclusive switch with last switch pressed
If multiple inputs are pressed  ( multiple outputs occur in same sequence but REMEMBERS Last SWITCH INPUT released with Exclusive Output.

Outputs: 4 Bit Latch with exclusive state ( only 1 output SET after nano delay )


Proof of Concept in slow motion ( 0.1ns per second )

https://goo.gl/F3H7PT  ( Needs Java Approval in browser )