I’ve continued to poke around at the XaviX emulation and figured out what was preventing the Namco Nostalgia 1 TV game from running. Namco Nostalgia 1 contains Mappy, Xevious and arranged versions of said games.

(technical reason, the lda ($0a), y style instructions are expected to fetch the pointer from zero page ram, but the actual data pointed to needs to be fetched from ROM, at least for upper banks)

The Nostalgia collections also make aggressive use of the screen clipping registers, for whatever reason in the Mappy remix the developers decided to clip the house to a single pixel at each side of the playfield, even if the full house is present in the graphics. I implemented the clipping based on other games, but it seems like I was clipping a pixel too much off the left side, so in the video I recently uploaded the left border is missing. Not clipping that column of pixels does result in an unwanted space where you can see the background between the status bar and left edge in Snowboarder, but I have a feeling that would happen on hardware, and Mr. Do’s videos of the Nostalgia games are of far higher quality than any of the Snowboarder (non SSX version) so I’m going with what the better videos show as evidence.

Interestingly the high score handling on both the Mappy games in this collection appears to be broken, showing the high score as ’00’ or ‘000’ in / when the high score table is presented rather than the true high score. I thought this was an emulation bug, but again checking Mr Do’s original hardware videos the exact same thing happens there. I’m not sure what happens if you beat the real score, possibly that fixes it, unless high scores simply don’t work at all?

Below are some screenshots of the boot screens and the arranged Mappy game, which plays like an Arkanoid style game where holding the button down at the right time gives you extra jump height (but don’t do it 3 times in a row as your rope changes colour and will snap if you attempt to do a high jump while it’s red)

The Xevious arrangement takes the form of a flag collection / bombing run style game, where you’re rushing to the end of stages against a clock with various things slowing you down rather than outright killing you.

The classic versions of each game run too

Fixing the bug that was causing Namco Nostalgia 1 to not boot also allowed Radica’s Baseball 2 to show some screens, although I haven’t got the analog inputs hooked up, so it isn’t yet playable.

Adding EE-PROM support allowed Excite Fishing to show a few more screens, before moaning about the EE-PROM again because presumably my hookup is still incorrect (the Nostalgia games no longer moan either, but don’t remember your changes properly even if they do write them to the EE-PROM)

I also started looking at the Super XaviX a bit, which needed additional opcodes etc. implementing in the CPU core. The most impressive progress with that one is Dirt Rebel MX, where the menu screens are fully functional, and the game even seems to control, but graphics need work (definitely needs raster interrupts for the road rendering)

XaviXport Tennis also reaches ingame, although again probably needs raster interrupts to do the linescroll effect on the court, and also has no working controls other than a single button to advance through menus. This also runs in an interlace mode and sends the fields on alternating frames, which means the entire image shakes ups and down at the moment, I’ll probably have to figure out a ‘clean’ way to deinterlace and render in a higher resolution otherwise it’s migraine inducing.

Lord of the Rings shows some stuff, but appears to use DMA in a strange way, and doesn’t transfer a valid palette (and goes no further than these screens)

Dragon quest does similar also expecting a weird DMA behavior, but gets stuck on this screen instead (it does actually upload a palette, but I’d hacked up palette use for making the previous screenshots and not restored it)



Star Wars seems to make more extensive use of the custom opcodes and is currently not showing anything.

I’ve been doing a bit of work on the XaviX emulation in MAME (technology used by a number of Plug and Play TV Games) and in that time I’ve made some decent progress with the emulation. While still far from perfect (some graphical problems, no sound, poor performance) I feel there has been enough progress to show some of it here. Some of the most noteworthy things using the hardware are the Taito / Namco Nostalgia collections which were released in Japan in 2006.

Taito Nostalgia 1 contains “Slap Fight” and “KiKi KaiKai” and remixed versions of them.
Below is the remix version of Slap Fight which mixes Slap Fight with another classic, Tiger Heli, giving you the Tiger Heli ship instead of the regular Slap Fight one. Due to the compressed screen size this version of the game is very difficult. The KiKi KaiKai allows you to play as the main character from Bonze Adventure instead.

Namco Nostalgia 2 contains “Gaplus” and “Dragon Buster” again with remixed versions.
Below you can see the Gaplus remix “Gaplus Phalanx” where instead of shooting things you must capture the grey enemies while avoiding capturing the red ones (and not hitting anything in the process)






Taito Nostalgia 1 contains “Legend of Kage” and “Gladiator” plus the usual remixes of them. Below is Amazones, the remix of Gladiator. Note, with current emulation missing the EEPROM support the key assignments are invalid by default and get lost every time you exit the game, but they can be assigned each time.

Namco Nostalgia 1 still doesn’t run properly, so no shots from that one at the moment.

Outside of Japan the XaviX technology was used mostly by games with novelty controllers. Progress has been made on the emulation of some of those too.

Graphics were much improved in Radica’s Play TV Boxing, menus now look solid, priorities are correct, sprites fill the screen properly etc.

Radica’s Bass Fishing game no longer crashes when you enter gameplay, and no longer has corrupt text in the menus. Inputs aren’t fully mapped yet tho.

Radica’s Card Night no longer crashes upon reaching the main menu, and has more correct graphics. The glitch where it rendered a corrupt menu over the startup screens is gone too.

The Radica Madden & Football games now show their startup screens (EA license screen on Madden, Farsight developer screen on Football) and also prompt the player to throw the ball (not emulated) to start, rather than crashing at that point.

The e-kara things now have a scrolling screen and colours that aren’t garbage (although no inputs exist to get past this screen) and the Fisher Price ‘Rescue Heroes’ shows a startup screen now before crashing. Excite Fishing DX moans about the EEPROM.

Wild Adventure Mini Golf shows some startup screens before getting to an animated display asking you to swing the club to start (not hooked up)

Radica’s Baseball 2 shows it’s secret test menu, and also a startup screen, but crashes after showing the Radica Logo

Radica’s Ping Pong now boots, although you can’t serve.

Radica’s Monster Truck has improved priorities (although controls still aren’t hooked up)

Snowboard has some minor improvements but still needs the raster interrupt hooking up for the ground

While many of these still aren’t playable the progress over the last few days has taken most of them from doing almost nothing to looking much more like what they’re meant to be, and a much better picture of the overall hardware.

None of this would have been possible without Sean Riddle dumping the majority of these titles and Peter Wilhelmsen purchasing many of them for that purpose.

The Steel Force changes mentioned in the previous update didn’t make 0.202, but should be in for 0.203, but I wanted to take this opporunitiy to highlight some more small changes that will be also be in 0.203.

I said before it’s not always ‘low profile’ titles that get fixes, and the last week or two has seen some bug fixes to better known titles that are just as important.

First I’ll start with CPS3, and a long-standing bug with the combo meters in JoJo’s Venture / JoJo’s Bizarre Adventure. This is one that back in the day I didn’t really put any research into due to unwanted attention and misuse of MAME for commercial bootlegs, but given that its been 10 years, the hype has died down and people still wanted to see it fixed, I decided to give it a look.

Actually a fairly simple problem. The game is only capable of displaying one Combo counter at a time, draws them off screen and uses ‘rowscroll’ to ‘bounce’ them into the display, so not only was the 2nd combo meter missing (because it never got scrolled on) but the ‘bounce’ on the Player 1 side was missing too, which was a dead giveaway for what the problem was. I was actually looking at CPS3 already with a view to fixing some of the palette manipulation effects in the later (P2 side) stages of Red Earth so fixing this was just sidetracking a bit. I might do an update about the palette stuff in Red Earth if I figure that out too.

The next piece of work isn’t mine, but that of Mooglyguy (Ryan Holtz) and happppp. This concerns the ‘Mirror Mode’ in Rave Racer (as well as the rear view mirror and a number of elements in other System 22 games)

To active mirror mode you should enter a code during the 3-2-1 countdown at the start of a race. Once this countdown appears, quickly turn the steering wheel RIGHT then RIGHT again, then press the BRAKE and GAS pedals together. If done correctly the display will instantly flip. To do it in MAME without analog controls you’ll want to set the digial speeds, sensitivity and auto-center speed on all the controls up high (100 did the trick for me)

Previously the mirror view did not properly flip the screen, but instead acted like the screen was flipped without showing the effect, meaning it basically just played with reversed controls and the speedometer needle in the incorrect position. Mooglyguy researched the issue, and happppp worked out how to implement it in the driver. Some optimizations were made at the same time meaning the driver also performs a bit better than it did before.

So there you go, two fixes to the emulation of some better known platforms that will be in MAME 0.203 and higher.

Not covered here in pictures, but equally important are some changes smf has made to the Playstation GPU emulation, fixing bugs in Silent Hill (non-arcade) as well as Psyvariar, the latter which was rendering the game near unplayable on later levels due to intense flickering of the background graphics (that fix is in 0.202) Again this is a ‘higher profile’ change due to the popularity of the home system and because many popular arcade titles made use of Playstation based hardware. The Psyvariar fix is timely too because of the massive improvements in the sound emulation the driver received recently (far surpass anything that could be classed as ‘Little Changes’)

It always annoys me when I read people making claims that there are only a ‘handful’ of fixes in the newer MAME versions compared to those that people are running on awfully underpowered devices like the Raspberry Pi; versions so old you’ll be stretched to find any active developer who even considers them to be the same project as MAME anymore.

Most of those versions are based on versions somewhere between 15 and 20 years old, and it would be more accurate to say there have been a handful of fixes every single week since then, many graphical, many directly affecting how the games play. The recent work done on the emulation of various protection chips is a good example of where the older versions are going to have fundamental gameplay flaws, with Operation Wolf in 0.201 being the latest in a long line of example.

The Super Shanghai Dragons Eye fixes mentioned in a previous post are also an example of an improvement that might otherwise slipped under the radar, and the post before that about Chrono Soldier shows how documentation of what’s what in those older versions is wrong too, with them presenting what turned out to be a prototype as the final game.

It doesn’t stop there tho, Steel Force is a game I emulated for MAME 0.58, which was released on 05 Feb 2002. I was watching one of LordBBH’s MAME Roulette streams where he ended up playing the game and noticed that on one of the levels there was a priority bug. I hadn’t noticed this issue before, so I’d never considered fixing it. Having noticed it, I decided to take a look at making a few improvement to the driver, and ended up fixing the priority bug while also improving some scene transitions I noticed were faulty too.

It’s subtle, and a lot more obvious when in motion because they move at a different speed, but the screenshot on the left has some ugly ‘oil’ bubbles over the ground, which should be part of the background and hidden under the ground layer.

There are still potentially some alignment issues with the game, as a few scenes do still look a little rough at the edges of the screen, but such bugs are commonly found in games due to safe areas, overscan and the like. The ending text for example doesn’t quite fit with the current visible area / alignment. This may, or may not be a bug in the original game, it doesn’t look like a great deal of effort was put into this screen, the developers even managed to misspell the title of the game as ‘STEELF FORCE’ The problem is there are very few high quality original resources for these games to use as reference.

So, anyway should you want to experience this game without ugly scene transitions and without the priority bugs, 0.202 or higher is going to be required.

Other little changes have been made over the last week or so too. I emulated a game called Pitapat Puzzle (which I need to write about at some point) and that allowed me to fix some video banking issues in later levels of the ‘Die Break’ game in ‘Bestri’ which is actually one of the most genuinely enjoyable Korean breakout clones. The bonus stages take the form of a Space Invaders style round, and if the ‘Girls’ dipswitch is enabled, are meant to show some non-erotic artwork rather than the usual grassy fields etc. Not only was the banking incorrect, but the later graphic ROMs weren’t even being loaded correctly. This one has been incorrect since MAME 0.113u3 (22 March 2007) which is when it was first added, and I had no solution to the tile banking at the time.

Left is MAME 0.201 and below, right is what will be in MAME 0.202 and higher.

Anyway, there’s a common theme with these things. On the surface the games appeared to be just fine, you could fire them up, and play them, with no obvious issues in the first 10 minutes of play, but once you started to get a bit further into the games you’d encounter an increasing number of problems.

For Super Shanghai you’d have to complete a handful of stages to get to the glitched cutscenes and priorities, for Steel Force you’d have to complete a bunch of levels to get to the broken priorities, for Die Break (Bestri) you’d have to complete 9 stages to see the issue. For Chrono Soldier you’d have to know about the game, and complete at least 3 stages for it to become apparent that the old version is massively incomplete. For Operation Wolf you’d have to play the game, possibly even reach right before the final boss to see it glitch out (although if you were using anything more than a year old the problems were significantly worse)

These are all little changes from an end user point of view, but when you consider that (aside from Operation Wolf) they’re things that a single developer has fixed in the space of roughly a week then multiple that by the number of developers, then further multiple by the number of weeks old each MAME version is and you can see how quickly the number of bug fixes adds up, and how it’s far more than a just a handful. The older versions aren’t “good enough” they’re downright awful for any serious use.

I get the novelty value of running the ancient versions on old devices, I get that it’s ‘cheaper’ etc. (although I find that debatable, as a Pi3 is 6 times slower in benchmarks than a throwaway 9 year old 3Ghz Core 2 Duo) but I still find it frustrating that people are recommending such versions and hardware for serious MAME builds. Once anybody starts playing on one, even running just the classics, you start to hit a mountain of bugs even if on the surface they look ‘good enough’

Sure there are regressions in new versions too, and some of those do frustrate me, but the overall trend is towards many more things working better, and regressions do get fixed.

A lot of the progress in MAME doesn’t get detailed writeups (because really, we’d rather be fixing things and improving the emulator) but it’s still there, happening all the time, just like the stuff I have covered here.

Around 5 years ago MAME 0.150 was released (17 September 2013) and in this release was a rewrite of the Data East protection chip handling, which allowed many previously problematic games that ran on Data East hardware to run without hitting protection related issues. To me it was one of the biggest advances in emulation at the time because quite a number of games made very devious use of the protection.

At that time there were two sets of Super Shanghai Dragon’s Eye dumped. The first was an English language bootleg that partially worked, but appeared to have buggy code where the bootleggers had missed protection checks and not reworked certain elements for the bootleg hardware properly. The emulation was imperfect, and trying to figure it out wasn’t helped by being unsure which bugs were emulation bugs and which were errors that would happen in the actual bootleg.

The second set was a Japanese set of the original game, which prior to the Data East protection work previously mentioned, had not worked properly either as various protection checks were failing.

Once the new protection code was in the Japanese set became playable, but had a number of graphical problems, and it wasn’t 100% clear how things hooked up because the existing hookups in the driver were based around the bootleg, which wasn’t quite the same as the original hardware, and some bad assumptions had been made.

While the game worked well enough to be marked as ‘Working’ in MAME the palette and priority issues were annoying, however, due to interests wavering, the driver got put on the back-burner and remained there ever since.

A recent dump of the original, non-bootleg English language set however prompted me to go back and look at the driver, and looking at it with fresh eyes I was able to spot some really quite obvious errors and reimplement the priority and mixing in a way that actually works for all situations.

Left old emulation, Right new emulation

MAME 0.201 and below	MAME 0.202 and above

The emulation of the bootleg was also improved, and benefits from the priority fixes, however there are still a number of other glitches, such as it not clearing the text in certain situations, and hanging at the end of the intro text until you press a button in quest mode. These appear to be cares where the bootleggers failed to deal with the protection properly as previously mentioned, so very likely happen on the bootleg hardware too.

Interesting note unrelated to the emulation: using the infinite ‘helper’ cheat isn’t actually very useful as the game always ends up recommending the first pair it finds, not the best, which inevitably leads to you failing levels.

and yeah, I know it’s a Shanghai tile matching game, and everybody seems to hate those these days, but all drivers need attention :-)

“Toki no Senshi – Chrono Soldier” has been supported in MAME for the longest time. It’s a Sega System 2 game, and records would indicate that it was added in MAME 0.34b3 which was released on September 17, 1998, so give or take a couple of weeks, 20 years ago.

What nobody seemed to have noticed in those 20 years is that the dumped version of the game was actually a prototype, and that the original hadn’t actually been dumped. There was a note in the source added more recently saying that the existing set was possibly a bootleg, because an original board had been observed with an encrypted 317-0040 module and the code we had was decrypted, but nobody had noticed that the build we had was a very different version of the game.

The PCB with the encrypted CPU module was dumped recently, so I bruteforced the key (thanks to Sega’s weak random number generation algorithms that were used to generate the keys) and got the new set running in MAME.

There were already a couple of unexpected difference with the new dump; firstly not only did the CPU code ROMs differ, but the tile ROMs were also different, as was one of the sprite ROMs and the colour PROM. This is highly unusual.

Comparing the initial gameplay demo there were clearly some visual differences, so I decided to delve a bit deeper into it.

The more I looked, the more I started to become sure that the old build wasn’t a hack or a bootleg, but actually a prototype, with the new build being much more complete. First of all, let’s look at the level layouts in the old build that’s been supported for 20 years.

Older / Prototype build, Levels 1,4,5,8

I’ve grouped these levels out of order to make it clear that after level 3 the prototype starts recycling levels, in fact the first level gets used 4 times with different themeing and by the time you get to level 8 the theme / tileset doesn’t seem to be complete either.

Proto lv1	Proto lv4	Proto lv5	Proto lv8

Prototype build, Levels 2,3,6,7

As mentioned, the prototype starts recycling at stage 4, so there are 2 more unique stages, stage 2, which gets recycled at stage 6, and stage 3 which gets recycled at stage 7. Again the themes change each time to make the levels still look fresh even when they’re not. Note also the complete lack of background details here, it’s just a single tile repeated meaning that really only a single stage was 100% complete at this point in time.

Proto lv2	Proto lv6	Proto lv3	Proto lv7

So we can conclude that in the earlier build which I’m dubbing a prototype, there is very little variety in the levels (3 complete foreground / object placement layouts, 1 complete background layout) and the final theme doesn’t even seem to be complete.

Final build Levels 1,2,3,4

Now if we look at the new dump “Toki no Senshi – Chrono Soldier (MC-8123, 317-0040)” the new set, which came from a board with proper Sega EPR numbers and an encrypted 317-0040 module you can see that the level design has evolved quite a bit. I’ve kept the levels in order this time because no level layouts are recycled (so I don’t have to group to make the point). As you can see, Levels 1,2 and 3 are basically the ones from the prototype but with improved background details etc. It was after that point the prototype started recycling levels, however, level 4 here is a brand new layout, not present in the prototype at all.

Final lv1	Final lv2	Final lv3	Final lv4

Final build Levels 5,6,7,8

Again, we have completely new level layouts here, the bosses do still cycle, just like in the older build, which is slightly disappointing, but the level designs for these later stages are significantly more challenging (or frustrating depending on your point of view) There is reuse of one of the visual themes (stage 5 and 7) but overall you can see that there’s a lot more content here than in the prototype build. The final 2 levels are still a little lazy, with level 7 having a background with no detail and the level 8 theme being a palette swap, but it’s likely there was no time left to develop them further and the actual level designs being unique was probably considered ‘good enough’

Final lv5	Final lv6	Final lv7	Final lv8

There are other differences too, the new set actually has a staff screen when you complete it, and the high score table correctly shows that you reached round 08, not round 01 in that case too.

compare that to the old set, no ending, incorrect level shown.

The new set also has a test mode, while the old one will just give you a black screen if the test dipswitch is set. note, the video ram check fails tho, this appears to be a bug in the game code that was probably introduced at the last minute and not fixed before release.

Title screen is recoloured slightly (like most things between the sets) but mostly the same, left is final, right is prototype.

Overall you can see there are a lot of differences between these sets. I think 20 years must be a record for having something supported in MAME without realising it was a prototype and the final version was still missing.

Thanks to ShouTime for dumping this piece of history, it’s been interesting to look at and might have gone unnoticed for even longer without his efforts to get this stuff preserved. Prototypes are fascinating, but knowing the final versions of games have been documented and preserved is vital when looking back at our history.

btw I’m happy for The Cutting Room Floor to use any of this research / resources contained in the write up as they see fit.