16 August 2014

This is similar to other BMC games (bmcbowl.c, koftball.c, popobear.c), so it might help with the consolidation of their emulation, which is still preliminary.

The hardware features two tilemaps and a pixel layer, all with per-line horizontal and vertical scrolling (used in the dog race screen above, for instance). Plus some mild protection and a random number generator whose emulation is only sketched at the moment.

It turned out to be a poker-themed gambling game whose Chinese title should be romanized, I'm told, as Dongfang Shenlong (Eastern Dragon):

I rewrote the bmcpokr.cpp skeleton driver to bring to fruition the "unknown poker game" in there, developed by Taiwanese BMC and running on their own custom hardware.

17 April 2014

Rejoice! The crazy-rare Wyvern F-0 vertical shooter by Taito is finally in MAME, Guru dumped the ROMs, the game is preserved. It was a long time coming.

I remember very clearly reading about it on the Italian magazine Videogiochi (No. 31, pp. 62-63) back in 1985. It was mis-labeled as "Wyvern FQ" due to the title logo graphics, as you can see from the flyer (from The Arcade Flyer Archive):

Much of the appeal, and rarity, of Wyvern F-0 comes from the dedicated cabinet it uses. The game boards produce two separate video outputs that are sent to two different screens housed in the cabinet. A half-silvered mirror is used to mix the images from the two screens in such a way as to produce a pseudo-3D effect. Backgrounds and enemies on the ground are displayed in the lower screen, while player ship and enemies in the air are displayed in the upper screen. These appear to be at different depths to the eyes of the player, thus giving the illusion of sprites in the air floating above the ground.

To further enhance the effect, the cabinet also has two speakers. The sound of enemies on the ground is heard from the bottom speaker, while the sound of enemies in the air is heard from the top speaker.

Here are some cabinet photos taken from this site:

That said, it does appear to be possible to run the game on a standard cabinet with single monitor, as shown here:

As for the game, it's essentially an updated version of Namco's Xevious, including the distinctive target for bombing the ground, using the second button, with a few other elements also borrowed from classics of the era. For instance the third "loop" button from Capcom's 1942, used to quickly get out of troubles, is implemented here with an additional gauge at the bottom of the screen that gets replenished with time. Another not so common feature is the ability to control the vertical scroll speed by moving your ship towards the top (faster) or the bottom of the screen (slower).

End-of-level bosses (one of the novel features of Xevious) are rather easy to defeat by bombing one to three weak spots or will simply fly away after a set time, in that case replacing the next level boss. Enemy shots can be intercepted by the player's, which I believe is rather unusual. Power-ups, e.g. a fire enhancing pod or a shield can be obtained by bombing ground targets, including a few hidden ones like in Xevious.

Here are some shots from MAME, note that some sprites have wrong colors:

Video of the attract mode and the first two "levels":

MAME executable (Windows x64) freshly compiled to include the driver.

Hardware-wise, this is typical mid-80's Taito hardware spread over 4 PCBs: a CPU board (Z80 + protected 68705P5 MCU), a sound PCB (Z80, 2 x YM2149, OKI MSM5232) plus a video board and a rom board with just common logic (no custom chips). Sprites are 32x32 and use 4 8x8 tiles with a look-up table in RAM holding the actual tile indexes. Plus a background and a text tilemap:

The MCU, used for protection and not easily dumpable, is simulated only in the boot phase. I've spotted no obvious in-game issues in the limited playing I've done, and in some instances the values read from the MCU are indeed discarded by the game code. Alas, subtle or major issues under specific conditions are indeed possible.

The music has a recognizable character to it thanks to the excellent 8-channel MSM5232 sound chip. The soundtracks can be found on the Taito Music Collection CD: