it latches:
The 8816 basically consists of the FET array, supported by an internal 7-to-128 decoder and a latch corresponding to each switch. If you want to turn on a switch, just write the address and a set on/off bit, and voila: an X line gets connected to a Y line and stays that way until you turn it off or reset the whole thing.
(from http://microship.com/bike/behemoth/bikelab/910221.html )