Mesen - NES Emulator

[Sour]

Mesen is a high accuracy emulator for Windows/Linux/Libretro - as far as I know, it passes more test ROMs than any other emulator currently available.

It has most features you would expect from an emulator (save states, online play, cheats, movies) and a lot of advanced options (Rewinding, overclocking, remove sprite limit, custom palettes, stereo effects, support HD packs, automatic updates, etc.). It also includes a very complete set of debugging tools (including Lua scripting).

Download: https://www.mesen.ca/download.php
Website: https://www.mesen.ca
Documentation: https://www.mesen.ca/docs/
Source (GPLv3): https://github.com/SourMesen/Mesen
Releases: https://github.com/SourMesen/Mesen/releases

The current version is 0.9.8 - released on June 23, 2019.

[miker00lz]

This is an excellent emulator! Tons of features. Sound is great. It handled everything I threw at it, except for one little bug I found (which you're likely already aware of)... got a hang in Battletoads on the second level.

[Dwedit]

Joystick emulation has bugs. Seems to not respect the strobe status, and always shifts bits out after the first write. I think you need to make reads not trigger shifts until the strobe bit is cleared.

Example joystick reading code that shows the bug:

Code: Select all

	ldx #1
	stx $4016
	lda $4016
	dex
	stx $4016
	and #$FC
	tax

	cpx $4016
	ror a
	cpx $4016
	ror a
	cpx $4016
	ror a
	cpx $4016
	ror a
	cpx $4016
	ror a
	cpx $4016
	ror a
	cpx $4016
	ror a
	cpx $4016
	ror a
	eor #$FF

[tokumaru]

Sounds cool, but...

Any idea of what could've gone wrong?

[oRBIT2002]

Works fine here on my Windows 10 x64. Nice work!

[Dwedit]

It references System.IO.Compression and System.IO.Compression.FileSystem, and those should come with .NET 4.0 or greater.

[tokumaru]

It references System.IO.Compression and System.IO.Compression.FileSystem, and those should come with .NET 4.0 or greater.

Thanks. Looks like I don't have 4.5 installed, which according to the site, is required. Will try to install it now.

[Sour]

Thanks for the replies!

Wasn't aware of the Battletoads freeze on level 2, thanks for letting me know, I'll look into it.

Dwedit - It does look like the code for this is incorrect, thanks!

tokumaru - Not sure if you've had any success with installing .NET 4.5, but that's most likely the source of the error. Mesen uses .NET 4.5-specific features to read/extract data from zip files, which is the first thing it needs to do when starting up.

[miker00lz]

This how it looked when it hung on Battletoads for me:



It happened when I moved all the way to the top of the screen. Doesn't necessarily mean it's related, but that's when it did this in any case. The game ran perfectly until this point.

[zeroone]

Awesome emulator. Very impressive work.

As for Battletoads, many threads on this forum have been dedicated to that exact stage 2 freezing issue. The nature of the issue is not fully understood. Hopefully, further research will yield a new test ROM.

[tokumaru]

tokumaru - Not sure if you've had any success with installing .NET 4.5, but that's most likely the source of the error.

Yup, installing .NET 4.5 fixed it. It's a very nice emulator! The debug tools look promising.

The nature of the issue is not fully understood.

Isn't it just a scrolling/sprite 0 hit issue?

[zeroone]

Isn't it just a scrolling/sprite 0 hit issue?

Yes. And, it has been confirmed with trace logs. But, the test ROMs do not detect the problem. The details of the issue are not fully understood.

[zeroone]

@Sour

Could you provide a zip download link? Antivirus software does not like downloading .exe files.

[tokumaru]

Can't you temporarily disable your Antivirus?

[zeroone]

Can't you temporarily disable your Antivirus?

I can't