Re: [新聞] (WIP) David Haywood's Homepage
2018.01.11
"Have a Cookie"
As I’ve mentioned before Semicom was one of my favourite Korean arcade
developers. While Semicom games are often a bit rough around the edges, and
borrow ideas heavily from others they were original products and for the most
part are playable.
Hammy found he had a Cookie and Bibi 2 PCB that is actually rather
interesting, because it seems to be an earlier and generally forgotten
version of the game; I don’t like to use the word prototype, since it
probably isn’t, but it definitely seems to be rarer than the more common
version that was already in MAME. The giveaway that it’s an earlier set to
me is that it uses the old style Semicom logo, as found on Hyper Pacman,
rather than the newer Semicom logo found on the later games. Most of the
backgrounds are also different. Test mode is also even more incomplete (not
that it is complete even in the set currently supported, Semicom often just
didn’t bother to finish the test modes)
One of the other interesting changes is the screen positioning, the newer
version that’s already in MAME has the screen more centered, moving most of
the important graphics up by 8 lines and placing the image in the center of
the black borders, rather than leaving 16 blank lines at the top. Strangely
the title screen background wasn’t re-positioned in the same way, probably
an oversight by Semicom.
The other obvious change at surface level is the older set will do 1P vs 2P
versus mode on a single coin.
The game also expects different protection data, meaning it has different MCU
content, I’ve faked this for now but we need to verify it.
Overall this is a very significant revision and clearly shows the game at an
earlier point in development.
Here are some comparison shots, with the existing MAME set on the left, and
the set Hammy dumped on the right.
https://mamedev.emulab.it/haze/pics2018/cookbib2_mame_1.png
So yes, that’s a nice little piece of history.
I’ve also been working on emulating the Radica ‘5-in-1’ Space Invaders TV
Game. It’s a 6502 based device (that doesn’t appear to be a NES clone) but
has some very weird video hardware, and might have a custom CPU core as the
way the interrupt vectors work is non-standard. So far I haven’t managed to
work out how the graphics / sound actually work for most of the games,
although you can see it is running the menu, and you can just about recognize
Space Invaders. Weirdly the graphics are all stored in ‘pages’ that are 256
pixels wide, rather than as tiles, but the game appears to have tilemap like
structures in RAM. It might be there’s a DMA operation that converts the
formats.
https://www.youtube.com/watch?v=IHuBesDcs2E
One of the games in the collection is Qix, which handles video in an entirely
different way, writing directly to a framebuffer.
https://www.youtube.com/watch?v=rAB5K67Ob1o
There are plenty of reviews of this device on YouTube, including some with
decent quality footage captured from the original hardware such as this one
which will prove valuable for testing / reference.
What’s interesting is that the Radica Tetris unit looks like a similar piece
of hardware, and according to Sean Riddle, who is dumping these things,
contains the same CPU die in one of the globs (which are used instead of real
chip packaging) and also contains what looks like a ROM glob with the same
pinout as the Space Invaders one, however unlike the Space Invaders one it
lacks a 3rd glob. My theory at this point is the 3rd glob is actually
dedicated RAM / framebuffer just for Qix to use. Hopefully I’ll have a dump
of the Tetris one to look at soon as it might allow me to make more sense of
this Space Invaders one.
I do wonder if there were any other Radica TV games based on the same
technology, obviously the Genesis ones are just cloned Genesis hardware, but
there are a lot of other Radica products and they’re exactly the type of
thing MAME is well positioned to be emulating.
: "Bad Touch ’96"
: I decided to revisit one of my older drivers, Black Touch ’96.
: This was promoted to working last year after code anaylsis showed that the
: majority of the bugs in the game did not appear to be emulation issues, but
: just the result of some very bad programming.
: Examples of this include the game timer not working (it checks a variable in
: workram that never seems to be set correctly, so is reset to 20 every single
: frame) as well as enemies and other items ending up outside the area of the
: screen you can move to, walking on the backgrounds etc.
: The sound is driven by a PIC16C57 which was deprotected and dumped as part of
: the old pre-Caps0ff decapping project, but until now nobody had got around to
: hooking it up.
: I hooked it up, and it seems just as badly programmed as the rest, for
: example once it starts playing music in attract mode it never seems to send a
: command to turn it off. The choices of sounds are awful in many cases too.
: I guess the only really interesting thing about this hardware is that it’s
: basically cloned from the SNK ‘P.O.W’ hardware, but with the added ability
: to have 256 colour sprites. We’re also quite lucky to have the PIC dump
: because a lot of these PCBs no doubt just ended up being scrapped due to how
: awful the game is. There are a number of other Korean games with PICs driving
: the sound where they couldn’t be dumped at the time and we haven’t since
: sourced another PCB now that we have the capability to dump them. (the Tumble
: Pop rip-off Pang Pang comes to mind)
: Here is a video of Black Touch ’96 running in MAME with sound, you probably
: don’t actually want to watch it.
: https://www.youtube.com/watch?v=Dt6SVfJ_CJc
https://mamedev.emulab.it/haze/
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