A 74C925 is clocked by an optocoupler salvaged from a mouse. I added the resitors.
See attached circuit and please note: it works as shown.
Without changing existing hardware I would like to stop the clocking under certain circumstances that a 18F452 micro can recognize.
If I return the emitter resistor to a IO pin from the micro (available) I expect that a high output will keep CLK high and a low output will allow clocking.