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Hi everyone.
I recently bought an ACA1234 from Individual Computers. Knowing that previously developed A1200 CPU boards don't require any custom support libraries for Release 3.2, I'd like to know if this holds true for the ACA1234, too? In other words, should the generic 68030 library provided by Hyperion be used with OS 3.2?
Thank you for providing really well designed Amiga hardware! 
OS3.1.4 and higher make an effort to make you believe that you need the spport lib, mainly for MMU use. However, we recommend to NOT follow that recommendation, as it breaks compatibility with lots of software, mainly causing support work, annoyance among costomers and cost at the supporters side (that is: here!).
The best thing oyu can do is not to install the libs, and after installation, to comment out the line in startup-sequence that nags you to install the libs. This is not just true for the ACA1234, but for any 68030 accelerator.
This is an old thread but as I just got a ACA1234 should we still NOT install libs for 68030 in 2024?
I honestly am not sure what benefit the libs provide as I thought the software would provide the needed code for specific cpus.
I am seeing the error on boot up about the libs not being installed. I know I can comment this out, but just looking for the proper way to do it..
So while mucking around in the ACA500Plus, there is a setting to turn on MMULibs in the advanced profiles...
No idea what this does, but there are no more Lib errors on startup. I'm guessing it injects them in there somehow.
Clever Jens...... Very clever.....
I am seeing the error on boot up about the libs not being installed.
It's not an error. It's just a nag-requester. You can comment that out in the startup-sequence.
Activating the MMU on a 68030 slows it down a little. Further, it breaks some communication methods between processes (the Amiga is specifically designed to be a machine without memory protection!) and programs that probe memory spaces, use undocumented mirrors or similar. Yes, the ACA500plus allows adding resident mmu libraries, but you should really have a good reason to use them, like your own development environment with Enforcer-like tools.
Many of the OS3.2-specific MMU use cases are an attempt to shoehorn memory protection into the system where it was never meant to have that in the first place. The best reason in the 1990s to have the MMU activated was to use it for putting Kicsktart into Fastmem. This function has been implemented in all iComp accelerators at a faster rate, it's called the MapROM function. The mapper is located in the memory controller, which does the mapping in real-time, instead of using a lookup table for the MMU.
If you don't have a specific use (i.e.: You've missed the MMU before), don't activate the libraries.
Jens
Jens, your attention to detail is awesome. This is great information!
I have commented out the whole CPU check section of startup and disabled the MMULibs in the ACA menu.
What about the VBRMove 68020+ setting? Should we leave this off as well for speed tweaking? (I have no idea what this does)
VBRmove moves the address that the Vector Base Register points to. The higher processors really have such a register, and it's a good idea to have that point to an address in fastmem instead of 0, which is in chipmem. While activating this speeds IRQs up a little, there may be incompatibilities with older software titles that you boot from floppy. Those titles are rare, though.
The 68000 does not have that VBR, but the ACA500plus adds it in hardware. Another thing that it can be used for is the "quit" key for WHDload titles, which is why it's desirable to have that function, even if you don't own an A1200 accelerator.
So for this feature, I'd switch it on, and only switch it off if you experience incpmpatibilities (again, which is unlikely these days).
Jens
Since we're asking, what's the difference between the different VBR Move options and the ACA1234's "NMI protect"?
Not sure what you're referring to in terms of "NMI protect".
Jens
Not sure what you're referring to in terms of "NMI protect".
Jens
The VBR setting in the ACA500Plus. There are 2 options, 68020+ VBR Move and 68020+ NMI Protect.
Lineof7s is trying to figure out what the difference is in those settings and what we should be using?
I see omniphil got here before I did, but yes.
This option in Normal Mode Expert Menu was introduced when I connected the ACA1234 to the ACA500plus. I've found explanations in the Wiki on what the VBR move option does, but nothing on "68020+ NMI Protect".
NMI protect is not specific to the ACA1234 (that's what confused me!). The NMI protect function is essentially a "clean return from NMI", which is not implemented on the Amiga unless you have launched setpatch. Since on some computers - depending on Paula revision - the IPLx generation isn't perfectly in sync, there may be so-called "spurious IRQs", which the OS normally handles OK, but as NMIs usually never happen on the Amiga, these can lead to crashes. If you activate the "NMI protect", you don't get such a crash, even if you haven't launched setpatch.
Jens
So... if Setpatch is part of the startup-sequence, under what circumstances (if any) would you suggest that option should be turned on?
I'd always activate it. It never hurts.
Jens
