Interested in learning 68000 hard/soft

Fred Cisin wrote: The family consisted of the Z80 only models II and 12, and the Z80/68000 models 16, 16B, and 6000. I recently spent some time reverse-engineering multiple versions of the boot ROMs and portions of TRSDOS 1.2 and 2.0. (Note that Model II TRSDOS is quite different than the more well-known Model I and Model III/4 TRSDOS, although there are similarities.) Not to disparage anyone else's efforts, but when I say "reverse-engineering", I do NOT mean that I just ran it through a disassembler and sprinkled in a few labels and comments. I mean that I turned it into something that can plausibly be considered to be source code. This is, of course, a lot more work. The Model II family hardware was in most regards better engineered than the Model I/III/4 consumer-grade machines. In the 16/16B/6000 systems, it was perhaps somewhat of an advantage to have a Z80 to serve as the I/O processor (although TRSDOS-16 failed to overlap any processing), but it was also somewhat of a disadvantage in that the 68000 could not access I/O devices directly at all, even in cases where that might have improved performance. Another problem was that the 68000 subsystem was designed to be able to interrupt the Z80 to request service, but because this only worked in machines sold as the Model 16/16B/6000, and not in upgraded Model II/12 machines, the software generally was not able to take advantage of it. On the other hand, the Z80 could generate interrupts to the 68000 on all machines. There were three generations of 68000 subsystems in these machines. Originally there was the "long card" version, which ran at 6 MHz. This was replace with a "short card", and then with a higher performance card. They are not 100% software compatible, alas, so there are limitations on what version of Xenix runs on what card.