That's an interesting question. From reading the documentation [1], the Trident disk should co-exist with the standard disk. It uses different microcode tasks (3 and 15), requiring additional microcode. No wiring change is mentioned (or discussion of booting off the Trident disk).

It seems like the Trident drive shouldn't be causing us any problems, but it's possible there's a wiring change or different PROMs. I guess we'll find out...

[1] http://bitsavers.org/pdf/xerox/alto/ifs_trident/TriconDoc.pd...