in case you are interested to test new fpga accelerators for a600/a500

[JimDrew]

I'm interested in the A500 version, although I will miss my VXL*30.  

[JimDrew]

FUSION does not need a MMU, but a MacII and later emulation requires complete 68020 emulation, which means all extended addressing modes, CAS, CAS2, etc.

[JimDrew]

The MacII (and later) all run in Supervisor mode, not user mode like the Amiga.  However, the Mac can jump back and forth.  Traps are used to get in and out OS calls.  Traps are also used on the Atari ST.

So, as we have learned with the FPGA Arcade Replay project, you just need to support every single 68020 instruction and addressing mode, and then everything works.  

[JimDrew]

ORI.L #d16, does not allow trapping of CMP2.B and CHK2.B
ANDI.L #d16, does not allow trapping of CMP2.W and CHK2.W
SUBI.L #d16, does not allow trapping of CMP2.L and CHK2.L
ADDI.L #d16,  no conflicts
EORI.L #d16, does not allow trapping of CAS.B
CMPI.L #d16, does not allow trapping of CAS.W and CAS2.W

While most of these instructions (with these operation sizes anyway) are likely to be rare even on the MacOS (and all should be deprecated IMO), I don't know if they are used on the MacOS so they could pose a problem. I wish Jim Drew had found his list of MacOS instruction frequencies he said he made years ago.

I looked through even my Syquest cartridge backups and I could not find that info.  

I can tell you that the MacOS uses ALL of the above instructions.

I will chat with Derek (emulators, inc.)  I might have given the instruction frequency info to him when I sold FUSION-PC to his company.