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Edstrom, R. Belmont
Total Likes: 2
Original Post (Thread Starter)
by AgentB
Hi all. I've been working on the driver for the AT&T UNIX PC, a 68010 based UNIX machine with a custom MMU released in 1985 made by Convergent Technologies. I've been hooked on this machine (it was the first UNIX machine I ever used back in the early 90s) so wanted to see if we can get it supported in MAME. I'm new to the MAME codebase so it's been a bit of a learning curve.

I've been spending a lot of time on this driver and made it through a number of hurdles. I'm finally at a point where the kernel is attempting to page fault and read new pages in from disk. However it looks like the current 68k code doesn't handle the case properly for a 68010.

I can trigger:
m_maincpu->set_input_line(M68K_LINE_BUSERROR, ASSERT_LINE);
which calls m68k_cause_bus_error() which does:
m68ki_stack_frame_1000() // 68010 specific

This is all fine and good. But I believe I need the DA registers saved and restored when a bus error occurs so the original instruction is run again after the page is brought into RAM.

execute_run() in m68kcpu.cpp covers this situation for m_pmmu_enabled, but not for the 68010.

Anyone able to help with the 68k code to support this 68010 with custom MMU scenario? Or is there something I'm overlooking?

Thanks so much, looking forward to making some further progress on this.

Liked Replies
by AgentB
Originally Posted by R. Belmont
Right, if you check the FreeBee site they credit several of their emulation advancements to "Jesse", who is the OP on this thread smile
lol, indeed that is me. My goal is to help get the UNIX PC running in MAME. Long term I'd also like to work on the Convergent Miniframe driver as that is a similar precursor machine to the UNIX PC.
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