One of the great things about having a fully merged MAME/MESS project is that it gives exposure to some things that might otherwise be missed.

plgDavid recently picked up (for the costly price of 600$) the last remaining undumped Casio PV1000 game cartridge, a port of Universal’s Lady Bug known on this platform as Fighting Bug.

The PV1000 was a simple system and received basic but original ports of a handful of arcade classics from around the period it was sold.

There isn’t really a huge amount I can say about the game, it’s Lady Bug, it plays a decent game, if you didn’t have access to an arcade then it would have been a nice piece of software to have at home back in the day. I’m glad to see it’s been preserved.

Anybody familiar with the MAME emulation of various Gaelco games will know that the big stumbling block for a many of them is the DALLAS DS5002FP security / suicide chip present on a lot of the PCBs.

In fact the only reason the game World Rally is emulated at all is because Gaelco directly provided the internal code of the security chip for that game (but no other games unfortunately)

The other working Gaelco sets are all unprotected versions, and even when we have both an unprotected and protected version of a game the protection is so well embedded that trying to simulate it is a nightmare.

We thought we’d actually got all the known unprotected versions of Gaelco games already, that was until system11 spotted an unprotected version of ‘Glass’ with an additional ‘Version 1994’ subtitle displayed on the title screen. Naturally he picked it up to investigate further.

The board has PROMAT stickers on the program roms, and the pictures of girls used ingame have been replaced with Anime drawings, no nudity. It looks very much like this version was created for the Korean market, presumably a year later than the original release when protecting it wasn’t considered such a high priority. The PCB lacks any of the components relating to the security.

As this version is completely unprotected it runs fine in MAME

Eco Fighters is a shooter released by Capcom in 1993, it can be seen as a spiritual successor to Forgotten Worlds in that it’s a horizontal shooter with a rotatable character.

One little known fact about the game is that it supports Spinner as an input device, however this configuration was exceedingly rare in the wild and for a long time it was thought a special romset was needed in order for the spinners to function. As a result most people are used to playing the game with a Joystick which doesn’t give anywhere near as precise control, especially irritating to players of the game was the fact that the attract demos were clearly recorded with an analog device (a Spinner).

As it happens no special romset is required at all, an otherwise unused bit in the input ports specifies that the Spinners should be used, and by feeding the correct analog inputs with that bit set the game plays as it was meant to be played.

This discovery actually came to light as a result of 3rd party spinner kits that were being sold for use with the game, allowing it to operate with Forgotten World style controllers. While the official Capcom spinner kit for the game is very rare (and thought to possibly have only been used on location tests) the unofficial kits are actually fairly easy to get hold of, and to our surprise didn’t require any kind of modified romset to function.

These kits prompted me to take another look at the game code, with the new knowledge that when the spinner is plugged in it should change the display of the test menu to show ‘Rolling’ instead of the P2/P3 buttons. I was able to quickly located the bit controlling this, and from there the pieces fell into place. The problem before was that we were looking for a way to enable a test mode control type option for the Spinner (like Puzz Loop 2 has) but it seemed like if there ever was one it had been removed from the code leading me to conclude that the versions we had no longer supported a spinner, I’m glad to have been proven wrong over this!

I can only assume the spinner for the original is rare due to cost cutting at Capcom, anybody who has played this with a Joystick, or attempted to play Forgotten Worlds without the spinner (using a keyboard / joystick in MAME, or on some stupid multi-game arcade setup without the proper controls) will tell you that it’s not an enjoyable experience, many spots in the game rely on you being able to make fast and precise movements to snipe down enemies.

Here’s a quick video of the game running in MAME with spinners (best watched at 60fps to get a good idea of the smoothness of the movement)

In the comments of my update about Nostradamus an original reference video for another game I’d emulated a long time ago was posted. That game was Aquarium by Excellent System, the video was this one by YouTuber ‘zu4989’

The post was made in relation to an audio issue in the emulation, now, the driver was done long before I really had any idea how to hook up audio chips, so that side of thing was done by somebody else (R. Belmont from memory?) but with a better understanding of these things myself now I decided to take a look.

The basic issue was that the wrong music was being played at the wrong times.

Initially I thought it might be a simple case of a bad modernization, old versions of MAME required you to leave a gap in the CPU region where you loaded a ROM if RAM was present for 8-bit CPUs (Z80 etc.) Newer versions don’t have this flaw and as a result a lot of drivers were cleaned up to remove that hack and handle things properly, it looked on the surface like the rom loading on Aquarium had been updated, but the modernized banking code was pointing to the wrong places (it was looking for 7 banks of 0x8000 from an offset of 0x18000 in the z80 region, which actually exceeded the size of the region and could have potentially caused crashes if the final banks were actually banked in)

However, even fixing that, the music did NOT match the reference videos provided.

Looking more closely at the banking writes the game was making revealed a little more, we were using the bottom 3 bits of the register, so writes of 0x00, 0x01, 0x02 … up to 0x07 would select different banks. What the game was actually writing was 0x0, 0x1, 0x2, 0x3 and 0x10, 0x11, 0x12, 0x13, nothing else. At this point it was clear that we were using the wrong banking bits, the correct bits to use were the bottom 2 bits, and the 4th bit.

Each bank contains a difference piece of music, so by cross-referencing with the video again I was able to establish which bank write related to each real bank, and re-order the above bank select bits into the proper bank value (bit 0x01 -> 0x01, bit 0x10 -> 0x02, bit 0x02 -> 0x04) with that done, the music was fixed. This scrambling isn’t too surprising, the driver already had a descramble function for the OKI commands.

I’ve recorded a video of the game with the correct music being played, (CHEATS ARE ENABLED TO MAKE DEMONSTRATING ALL THE LEVELS EASIER) You can cross-reference it with the video linked above if you want

The reference video also showed a number of cases where our priority handling wasn’t correct, namely the top border should have been chopping the large fish sprites and wasn’t, the large fish sprites also needed to go under the insert coin text (already correct) but at the same time needed to be shown above the bottom part of the NEXT text. Furthermore the smaller sprites showing the next pieces to appear needed to go underneath the tilemap. All those cases were fixed. The background colour was also incorrect, this wasn’t really visible anywhere except on the Winners Don’t Use Drugs screen, but I fixed that while I was at it as it was obvious even without a reference.

Sometimes it’s difficult to know if the emulation of a game is correct without studying reference videos, and sometimes those reference videos don’t surface until much later.

That was the case with the FACE shooter Nostradamus, which has a number of video effects we didn’t know were missing until they were highlighted by somebody watching a 1CC (1 Credit Clear) of the game recorded from a PCB.

There were a number of effects, including a sprite masking effect and a shadow flicker effect missing, as well as the arms of the final boss (this one we did actually suspect was a bug for a long time, the PCB evidence provided confirmation)

I’ve uploaded a recording of the game after making several fixes to YouTube (the video has cheats enabled, it’s not meant to be a gameplay video) You’ll probably want to make sure you’re watching a 60fps version.

Here are some links to specific parts of the video
Stage 6 Boss appearing – This is a masking / stencil effect created by putting a sprite behind the background layer causing it to cut holes in other sprites without being directly visible

Stage 7 Boss appearing – This flickering shadow is not actually a sprite and is done by using the tilemap enable register, turning it on and off every few frames, previously the tilemaps were alwyas enabled and the shadow was displayed as solid.

Final Boss arms – The arms are priority 0 sprites, and due to the way we cleared the priority buffer to 0 they were never being displayed.

Luca’s addition of Trivia R Us to the Crystal System driver, and discovery that it needed the stack aligned reminded me of something I’d looked at a long time ago with ‘Donggul Donggul Haerong’ another Crystal System game.

I’d made an observation in the past that ram writes on most Crystal System games were aligned, except on the two non-working ones, which at the time seemed like merely an interesting co-incidence.

Looking back at it there might actually be more to this discovery than it first seemed, because patching out the unaligned reads/writes (simply disallowing them in the core) allows the game to work 95% of the time. Sometimes, for reasons unknown it still boots up in a broken state so there is a possibility that the unaligned writes are a symptom of whatever is failing, and causing the RAM corruption, rather than the cause of the failure, or there could simply be multiple issues.

Either way, if you boot the game and it starts without a problem (no graphical glitches) you seem to be able to play it now. Due to not being 100% reliable the game will still be marked as NOT WORKING in MAME, but it has definitely improved.

The 2 Player mode, which switches to a higher 640×480 (presumably interlaced) resolution also doesn’t work properly, it runs twice as fast as it should and only updates one of the playfields correctly, I suspect this is some kind of raster effect involving changing the scroll-values mid-screen and the driver *really* isn’t set up to support this.

It’s possible the CPU can’t do unaligned reads / writes, or possible that disabling them in the core is nothing but a gross hack, it’s hard to tell as other games don’t seem to use them at all, although I would appreciate people giving the other Crystal games a good workout in 0.168 to ensure nothing has broken, if it has, obviously this progress will end up being reverted.

The game is often described as a modern take on Wonder Boy from Korea, it’s easy to see why.

Office Yeo In Cheon Ha also stops crashing with these changes (although there are still some ugly graphics) however not all controls are mapped, so again that one can’t really be considered working yet despite the improvement.

I also moved 2 other games which are meant to be basically Crystal System hardware (same integrated SoC but slightly different surrounding hardware) into the driver just in case somebody like Luca is interested in looking at them too.