Haze: The Slow Road - 模擬器

另一款當年家喻戶曉的經典作品。

A bit of teamwork with Kale has seen some good progress made on Taito’s Sky
Destroyer.

The Famicom version of the game is at least these days a fairly well known
title as it’s featured on a good number of the NES pirate multi-carts, and
TV game systems. The arcade version is a more obscure title, luckily a PCB
showed up recently.

Like many Taito games of the era it’s protected, in this case by an 8741
MCU, much like “Cycle Mahbou” to which the hardware has several
similarities. Taito’s Gladiator also uses similar protection, although in
that case actually has 4 of the MCUs (the ROMs for those are dumped, but not
hooked up because in that case I believe the chips didn’t have their
security bits set, but the Sky Destroyer one is secured)

Anyway, the good news is that Taito typically used the 8741 MCUs as I/O
devices to communicate between CPUs and with some of the other devices on the
PCB. This type of MCU is easier to simulate with a reasonable degree of
confidence, and that’s exactly what Kale has been doing for Sky Destroyer
after he initially hooked up the basic sprite support etc. for it.

Now, so far, all Kale, which might lead you to wonder why I’m posting about
this at all, but let’s start by looking at an original video of the game.

Smitdogg posted a video of the game running on original hardware, the
observant of you will immediately notice the ‘gimmick’ of this game is the
funky tilting background, which in 1985 was an unusual effect and the main
difference between the arcade version and the Famicom one.

Now, clearly the effect isn’t a full ROZ (Rotate and Zoom) style thing like
Data East attempted to pull off in Zero Target, but it is still an attractive
looking effect. In the end emulation was actually relatively simple, the
first two byte of each row definition in the tilemap RAM region store the
vertical scroll values for 2 columns. Additionally there were values for the
horizontal scroll, and a single register to control colour cycling stored
nearby (keeping the CPU cost of producing the fancy background as low as
possible on original hardware)

Anyway, while Kale took care of the system emulation, including simulation of
the MCU I looked at the graphic side of things and hooked up the various bits
described above as well as fixing a few minor issues with the sprite
emulation. It’s worth noting that there is a bit of background / sprite
desync in the emulation, but if you study the original hardware it happens
there too, it’s especially noticeable when the island is coming up from the
horizon as the game attempts to fake the background effect using sprites to
give the impression of the island rising up by masking out the bottom part,
and you can see where things aren’t quite perfectly synced.

http://mamedev.emulab.it/haze/pics2012/skydest1.png
http://mamedev.emulab.it/haze/pics2012/skydest2.png
http://mamedev.emulab.it/haze/pics2012/skydest3.png
http://mamedev.emulab.it/haze/pics2012/skydest4.png
http://mamedev.emulab.it/haze/pics2012/skydest5.png
http://mamedev.emulab.it/haze/pics2012/skydest6.png

Currently the game lacks sound, this is because communication with the Sound
CPU is also done through the MCU device, however because the device appears
to be a ‘functional’ MCU acting as glue logic rather than providing game
specific data I imagine Kale will be able to get the sound working in short
order (actually he tells me it’s trickier than it looks) The game otherwise
seems to be fully playable.

Current emulation video as of the time of writing

http://www.youtube.com/watch?feature=player_embedded&v=hzlz0oCUbh4

(the final improvements to this, namely the color cycling and sprite fixes
didn’t make 0.146u4, so don’t be alarmed if you don’t get the same
results as the video)


來源：http://mamedev.emulab.it/haze/2012/07/30/burning-skies/

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