Trying to get FME-7 IRQs right

[koitsu]

I've now read the entire thread twice and I honestly can't figure out what the "correct" behaviour should be. Could we get a short/terse write-up that concisely explains what the proper behaviour should be? That should greatly help with submitted bug reports to emulator authors.

[lidnariq]

Correct behavior: All writes to register "D" (i.e. writing to $Axxx after $0D has been written to $8xxx) should acknowledge the IRQ, regardless of the value written. Writes to registers "E" and "F" shouldn't.

[tepples]

Watch this space for progress of fixing FME-7 acknowledgment:

• Nintendulator: In #nesdev, Quietust reports it fixed
• FCEUX: I filed a bug report, and rainwarrior committed a fix (diff; Windows interim build).
• Mednafen: I needed help with the registration form's CAPTCHA (and on identifying the mascot) on #nesdev, and then it took a while to receive registration confirmation from forum.fobby.net and a while after that for a moderator to approve the bug report.
• Nestopia UE: GitHub issue report has been closed with a fix.
• NO$NES: Haven't had time to download, install, and test, but the description of FME-7 in Everynes appears incomplete
• RockNES, BizHawk: Reported fixed below
• EverDrive: In #nesdev, tpw_rules said "krizz told me he'd fix it for everdrive"
• PowerPak: In #nesdev, loopy reports that he has updated the FME-7 implementation in the mapper pack I use.

[lidnariq]

Nestopia UE bugtracker: https://github.com/rdanbrook/nestopia/issues

[lidnariq]

Tested Nestopia UE patch:

Code: Select all

diff --git a/source/core/board/NstBoardSunsoftFme7.cpp b/source/core/board/NstBoardSunsoftFme7.cpp
index f3ee5d2..535456f 100644
--- a/source/core/board/NstBoardSunsoftFme7.cpp
+++ b/source/core/board/NstBoardSunsoftFme7.cpp
@@ -170,9 +170,8 @@ namespace Nes
 
                                                        irq.Update();
                                                        irq.unit.enabled = data & 0x01;
-
-                                                       if (!irq.Connect( data & 0x80 ))
-                                                               irq.ClearIRQ();
+                                                       irq.Connect( data & 0x80 );
+                                                       irq.ClearIRQ();
 
                                                        break;

[koitsu]

Nestopia UE -- filed issue 124

[zxbdragon]

You can provide the copyrighted FME-7 cassette transformed into flash cassette , The test results on FC/NES?

[Zepper]

RockNES seems OK.

To save 16 cycles during vblank.

To eliminate unofficial opcodes as a factor in the test, I have added a second build-time option called AVOID_UNOFFICIAL_OPCODES, in addition to the existing build-time option called NESTOPIA_WORKAROUND, and built two more ROMs without unofficial opcodes, one with and one without the Nestopia workarounds. The ROMs built without unofficial opcodes behave (or misbehave) the same way in Mednafen as the corresponding ROMs with unofficial opcodes.

Works fine in RockNES now. The Nestopia version flashes the bottom of the image (around 40 or more lines).

[zeromus]

fixed in bizhawk's neshawk and quicknes cores in r9193

[koitsu]

Nestopia UE issue 124 has been committed/fixed.

Binaries are usually made available over on EmuCR except it seems the last build they've offered is from 2014/10/07. I don't know what changed to make them stop doing builds, but I'll see if I can find out.

Edit: seems the builds on EmuCR aren't of master -- they're only when a new tag (I think) is made; the 2014/10/07 release correlates with the last/latest git tag 1.46.2. I'll see about asking if they can add one for master.

[FrankWDoom]

Does this still need testing on a real cart? I couldn't tell from the posts if someone actually did that.

[tepples]

l_oliveira ran it on a cart and got this result. The task has become to get emulators to give the same result.