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Posted By: Vas Crabb MAME 0.231 - 04/28/21 07:41 AM
MAME 0.231

MAME 0.231, our April release, is out now! The Yamaha FM synthesis rewrite is progressing, with the OPL family (including YM2413, YM3526, YM3812, YMF262 and Y8950) done this month. A number of regressions reported against the previous release have also been fixed. Most things should be improved, but if you notice something wrong with a system using one of these chips, be sure to let us know. Warp-1, a very rare Sun Electronics game from the late ’70s, has been added this month. This is an early example of an “into the screen” space shooter.

For as long as it has been emulated, the “3D” stages in Contra have been too easy. This comes down to the functionality of the Konami 007452 chip, which Konami calls a VRC&DMP. Now we know that VRC stands for Virtual ROM Controller, and controls ROM banking. However, the DMP part has been more of a mystery, assumed to be some kind of protection. This month, furrtek worked out that it’s apparently some kind of Divide/Multiply Processor, for 16-bit maths operations that would be unacceptably slow on the games’s pair of 6809-family CPUs. The great news is the game now runs correctly, the bad news is you’ll probably die a lot more.

David “Haze” Haywood is back this month with fixes for several arcade games that have never been quite right. He’s fixed graphical priority issues in SNK’s Beast Busters and Mechanized Attack, improved timing in Seibu Kaihatsu’s Shot Rider, and corrected layer offsets in Mitchell’s Funky Jet. He also added support for a couple of protected Mega Drive bootleg games from Argentina. Recently, David has been streaming MAME gaming sessions, often highlighting under-appreciated games. You can watch the recorded streams on his YouTube channel. Still on the topic of things that have never been right, sasuke has been busy this month. He’s improved the Nichibutsu 1412M2 DAC playback rate and timer period calculation, most noticeable on the Mighty Guy soundtrack, and made Taito’s unicycling game Cycle Maabou playable.

That’s all we’ve got time for here, but you can read about all the additions, bug fixes, and enhancements in the whatsnew.txt file. As always, the source and 64-bit Windows binary packages are available from the download page.

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Posted By: Richard Bannister Re: MAME 0.231 - 04/28/21 10:23 AM
For someone who hasn't been following this closely, what is the thinking/reasoning behind the Yamaha FM rewrite?
Posted By: etabeta78 Re: MAME 0.231 - 04/28/21 11:09 AM
It's mainly to have an up-to-date core under a more permissive license, so that commercial ports using MAME for other aspects of the emulation can use MAME for sound as well (e.g. some recent Capcom Arcade collection which properly credited the project)
Posted By: R. Belmont Re: MAME 0.231 - 04/28/21 11:34 AM
Also the rewrites are incorporating the last 20 years of people pulling these chips apart and finding out how they work at a bit-accurate level. There are several games that never sounded right before and do now.
Posted By: Stiletto Re: MAME 0.231 - 04/29/21 04:42 PM
Official MAME 0.231 Twitter and Facebook links!

https://www.facebook.com/mamedev.org/posts/2835334466716208

https://twitter.com/mamedev_org/status/1387538232250880000
Posted By: Robbbert Re: MAME 0.231 - 04/30/21 01:33 AM
You wouldn't know it from the blurb, and I don't expect people to read the whatsnew attempting to connect all the pieces.

0.231 saw a number of improvements in TRS-80 emulation.

- Preliminary software lists added for disks, cassette and quickload. Since the system was reputed to have more software than the Apple II at one stage, users might want to flesh these out.
- Fixed disk booting for the Model 4
- Fixed the quickload (CMD), the rules for loading the data parts had mathematical errors.
- Due to the memory system upgrade, CMD was mostly crashing. It's been fixed for Model 1 and 3, but disabled for Model 4.
- Loading of CAS files has been fixed.
- Loading of CAS files for Level 1, and for Model 3 was added
- Added emulation of JV3-format disks - together with JV1, DMK and IMD, this allows reading of almost all available disks.
- You can choose which type of disk drive to use (via the slot mechanism). This fixed the IMD breakage after its recent modifications.
- Radionic, and LNW-80 have been split off to their own drivers due to hardware differences.
- The EACA Video Genie was added.

The drivers are still marked MNW because of disk-related issues. They can freeze when reading or writing, and they may crash when writing. I don't know if it's an emulation issue or a core floppy problem.
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