That's interesting, I was under the impression that Z8000 uptake was hindered due to bugs in it's implementation, do you have any references about this segmented architecture?
But you can read about the Z8000's segmentation on WP: "The Z8000 used a segmented memory map, with a 7-bit "segment number" and a 16-bit offset. Both numbers were represented by pins on the Z8001, meaning that it could directly address a 23-bit memory, or 8 MB.[4] Instructions could only directly access a 16-bit offset." https://en.wikipedia.org/wiki/Zilog_Z8000#Memory_handling
Many 16-bit systems around this time did this kind of thing. Makes it really annoying to do things like draw in a framebuffer bigger than 64k. It does look like at least the PC could hold a whole 23-bit address, so that's good.
The 68000 had a nice flat linear memory model and that made it much easier to write code for.