Nothing to forgive, but I thought you might not have made the connection when you encouraged me to post a FS message in Trading Post and I already had one there under my trag monicker.
Gamba's IIci ROM worked, but it may not solve the problem that you are seeing. I think we may need to actually decode the PAL on the IIsi/SE/30 adapter and figure out what it is doing to solve this problem. Hmmmm. Thinking along those lines, has this problem been shown with the IIsi ROM in the SE/30? The IIsi works with that adapter (presumably), so why wouldn't the SE/30, with a IIsi ROM.
I still have the ability to make the Flash chips with IIci ROM code on board. That is what I supplied to Gamba. I chose the chips and sent Gamba the specs. He laid out and fabricated the circuit board, with a little bit of advice from me (but not much) and I sent him the programmed chips, which he attached to the board. Shortly after that he disappeared. :-(
I don't have the ability to easily make the ROM circuit board, and none of the existing modules use a variety of chip which could be easily desoldered and replaced.
I do have a board layout designed for the ROM module which will be compatible with the incredibly common PLCC32 packaged flash chips. But turning that into a board would either require many more hours of fabrication than I will realistically be investing any time in the next 6 months at least, or somewhere in the neighborhood of $400 - $600 to pay someone like 4pcb.com to fabricate the design.
I also have the firmware code for the various Turbo040 versions extracted around here somewhere. Probably on the hard drive of that old Windows '95 machine that drives my chip programmer...
Anyone here the least bit skilled at reading Mac machine code or doing a disassembly? Come on, don't be shy. Raise your hands.
In this case, what I would hunt for is code at the beginning of the Turbo040 firmware which checks what the host machine identity is. The host machine identity is going to be taken from the ROM. So when a Turbo040 is in an SE/30, but the SE/30 is using a IIfx or IIsi ROM, then the Turbo040 is going to behave as if it is in a IIsi or a IIfx--if it has code to check the host machine identity. Apparently, this is not a problem except for floppy drive timing. Maybe. It's a decent hypothesis. If such a check is done, we could create a version of the Turbo040 firmware such that it uses the SE/30 results even when it thinks it is in a IIsi or IIfx.
Hmmm. The Turbo040 cannot go in a IIfx. There's no adapter for it. So what set of parameters is it using if it finds itself in a IIfx? I would guess that it is defaulting to IIci parameters, which would imply that using a IIci ROM won't get us any better results than the IIfx ROM does.
Another option would be to find the location of the machine identifier in the ROM code and change it to SE/30's code. As long as one is burning the ROM code onto Flash anyway, it would be easy enough to do a small edit before doing the burn. That is, assuming that the machine identifier is not located in many places.