David Haywood's MAME(tm) WIP (11/01/23 FixEight) - 模擬器

http://mamedev.emulab.it/haze/2011/01/23/theres-a-fix-for-that/

I posted the video yesterday, but didn’t have time to write the post to go
with it due to having to go out while it was still uploading. Anyway, here’s
the update.

Following on from Knuckle Bash, Dogyuun and V-Five, Robiza managed to decrypt
the Sound CPU code for FixEight, which uses a different encryption table.

Previously only a bootleg was ‘working’ and that had vastly inferior sound
hardware. (and a much lower CPU clock resulting in large slowdowns.)

Unlike Toaplan’s other games FixEight uses an EEPROM for settings / region
selection, which caused a few additional issues. I’ve helped Robiza with
most of these, and the game correctly loads and saves it’s settings from
EEPROM. The only thing strange is that the EEPROM that was dumped from the
original PCB appears to be non-functional with the code we have; there are
explicit checks for values stored in it, and they’re simply wrong in the
dump. Also due to Toaplan using a non-user-changable EEPROM setting for the
region in this we have to support the regions as a bunch of clones rather
than having the jumper switch if we’re to avoid using hacks in the code.

The Sound CPU in this instance also provides background data (they’re
contained scrambled in the program ROM, the V25 program descrambles them) We
knew that the sound CPU was involved with the backgrounds somehow, but weren’
t sure exactly. It turns out they use an almost identical method to the one
used to load the 2nd part of the v25 code on the other games, copying the
background data once at startup into shared RAM. Note, even the bootleggers
resorted to placing this data in an additional ROM because they couldn’t
figure out how the V25 descrambled the data from ROM.

I don’t think this is one of Toaplan’s better games. It’s meant as a
followup to the excellent OutZone but the environments are too
claustrophobic, and don’t give you enough room to shoot. Coupled with some
rather useless alternate weapons which just end up in a single direction, or
simply hitting the level environment instead of your enemies and you have
what can only be described as a frustrating experience. A Shame, because it’
s a very good looking game. The music isn’t even that good, although is
infinitely better than that found in the bootleg!

Note, the intro ONLY plays if the invincibility setting is set to ON. I don’
t know if this is because Toaplan decided to take the feature out of the
game, or if there is another revision with this condition / bug fixed. The
bootleg in MAME is the same. There is an explicit check in the code and the
bit to enable the intro is exactly the same as the bit to enable
invincibility! This seems illogical, but it’s the way it is.

The remaining Toaplan games (Vimana, FireShark, Ghox, Whoopee JPN version,
Teki Paki) will need the HD647180 MCUs decapping for proper sound emulation.
See The Decapping project for more information on this. Donations _are_
required if this work is to be done. Proper emulated sound will be far better
than the hacked in OSTs found in some other builds as has been shown with the
ones we’ve emulated here. As a programmer there is nothing more I can do for
those games, in order to emulate the sound, we need the sound code, which is
inside the MCU.

Chips 19, 58, and 102 are the Toaplan MCUs. Please note, he does not yet have
the MCU for Ghox, or the Japan Whoopee (although the latter I believe has
been sourced) Spares of the chips always help in the case of something going
wrong.

http://www.youtube.com/watch?v=4Ijz3-7l_A4&feature=player_embedded

( ￣ c￣)y▂ξ








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