No. They use multiple address spaces at an offset of $4000 for each clockport (base address is 0xd80001, which clashes with some chip area on A4000D/T machines -- peeking and poking in that area on an A4000 machine causes all kinds of havok to the IDE/SCSI port). Programmers that want to support these additional boards need to adapt their drivers for it and detection of multiple clockports that are not mere mirrors of the first one, is not trivial.
Hmm.. that sounds weird.. the official A4000(T) memory map lists $D00000-$D9FFFF as unused.. Maybe there's an address decoding bug somewhere in the IDE/SCSI logic then..
