Regarding those bidirectional latches we were discussing earlier. The official name is "registered transceiver" and the part number is 74xxx543, where xxx is whatever logic family they're in. So, for example, SN74F543 for TI's plain 5V version. Or PI74FCT543 for Pericoms fast 5V version. They support eight bits at a time.
Cool! It seems like those might just be the ticket.
It seems similar to other 5V Flash ROMs like the SST39SF, and the datasheet for that chip says more about what happens if /OE and /WE are both asserted. "Write Inhibit Mode: Forcing OE# low, CE# high, or WE# high will inhibit the Write operation. This prevents inadvertent writes during power-up or power-down." Later it says that when /OE is asserted (regardless of the other control pins) the DQ pins will be High Z/ DOUT.
Good catch! I missed that in the SST39F040 datasheet. It kind of seems like the unlock sequence should basically already be providing enough protection anyway, but I guess it makes sense that they added that as well...just in case...