KA630 guru?

I found the problem here; it was a totally boneheaded mistake on my part. Two of the IPCR bits are bits 0x0040 and 0x0020 - and I had coded up my IPCR emulation with those bits at 0x0080 and 0x0040. I moved them to the correct bits and all of a sudden it started working a whole lot better. After a bit of work, the selftest now gets much further. Now it falls over during test 4. I know exactly why, and I'm not sure what to do about it. It's turning on memory management (mtpr $1,$38). But it must be depending on some idiosyncracy of the chip, because the way the page tables are set up, the address after that is not valid after memory management is turned on. In physical memory, we have 00000200: moval 21e,r0 00000205: bicl2 $fffffe00,r0 0000020c: bisl2 $80000000,r0 00000213: brb 218 00000215: halt 00000216: halt 00000217: halt 00000218: nop 00000219: mtpr $1,$38 0000021c: jmp (r0) 0000021e: nop with this code entered by jumping to 200. But at this point, the way the page tables are set up... vax> v 21c 0000021c: P0BR 80000600 + 000004 = 80000604 -> SBR 00000600 + 00000c = 0000060c S PTE a4000004 = V=1 PROT=4=UW M=1 OS=00 PF=000004 -> process PTE physical address 00000804 process PTE 00000000 = V=0 PROT=0=NOAC M=0 OS=00 PF=000000 -> not valid However, as you can see, r0 will contain 8000001e at that point, and vax> v 8000001e 8000001e: SBR 00000600 + 000000 = 00000600 S PTE a0000001 = V=1 PROT=4=UW M=0 OS=00 PF=000001 -> physical address 0000021e So the code is obviously depending on the "jmp (r0)" getting executed even though it's not accessible after MAPEN is turned on. Either MAPEN setting is getting delayed or it's counting on executing out of prefetch buffers or some such. I'm not sure what I want to do about this. I can see two basic tacks to take here: (1) patch the ROM images to avoid this dependence or (2) try to emulate whatever the chip is doing. Tentatively, I'd prefer the latter. But that leaves me with another question: Does anyone know the KA630 CPU well enough to say exactly how it is this code manages to work? I can't write an emulation of something I don't understand, after all. :-) /~\ The ASCII der Mouse \ / Ribbon Campaign X Against HTML mouse(a)rodents.montreal.qc.ca / \ Email! 7D C8 61 52 5D E7 2D 39 4E F1 31 3E E8 B3 27 4B