Thread Like Summary
Edstrom, R. Belmont
Total Likes: 2
Original Post (Thread Starter)
by AgentB
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_init_exception()
m68ki_stack_frame_1000() // 68010 specific
m68ki_jump_vector(EXCEPTION_BUS_ERROR)

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.

Jesse
Liked Replies
by AgentB
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.
1 member likes this
Who's Online Now
1 members (Golden Child), 24 guests, and 3 robots.
Key: Admin, Global Mod, Mod
ShoutChat
Comment Guidelines: Do post respectful and insightful comments. Don't flame, hate, spam.
Forum Statistics
Forums9
Topics9,086
Posts119,087
Members5,014
Most Online890
Jan 17th, 2020
Our Sponsor
These forums are sponsored by Superior Solitaire, an ad-free card game collection for macOS and iOS. Download it today!

Superior Solitaire
Forum hosted by www.retrogamesformac.com