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The Dead of Slapstic - September 12, '98 by JoseQ
The last very awaited MAME was MAME v0.31. Why? Simply because there were no public betas before that. Why was this one of the greatest releases ever? A huge surprise came in the form of the Atari System 1 games. Nobody expected to play Marble Madness, Toobin, etc because there was this dreaded Slapstic chip that encrypted everything. Enter Frank Palazzolo, chip bounty hunter. With a mission set, and with Aaron Giles, as his partner he uncovered the workings of this mysterious chip and granted you the gift of playing those great games. With this as a topic, we directed our attention to Mr. Palazzolo to exchange a few questions about "The Dead of Slapstic".

1. Back to tradition, can you tell us a little bit about yourself, and what motivated you to get into emulation?

Well, I'm an Electrical Engineer working as a Programmer/Manager. I first heard about game emulators in early 1997, thanks to the Emulation Repository Web Site. I've always loved the old games, and in some ways they affected my career aspirations as a kid. (I always wondered what was inside those magical machines.) I worked in an Arcade in high-school, never thinking that these games would be all but gone someday. Today, being able to breathe life into this old technology is a lot of fun, a technical challenge, and it brings back a lot of old memories.

2. What keeps you working hard on it? Does it seem as exciting as ever?

Yes, actually it does. This hobby is fun for me on all levels. There are the technical challenges, both in understanding the hardware and software, like the slapstic. Then, there are the preservationist and nostalgic aspects. I like to collect these games, but I realize that many of them will be all but gone if people weren't doing this kind of thing. I'm glad my grand-kids are going to be able to see what these games were like 50 years from now. For me, it's like having dozens of irresistable puzzles to work on, AND having a great motivation to work on them.

3. What are your current projects (drivers?), and aspirations?

I like to work on audio, older games, and games with unusual hardware. I tend to jump around a lot! :) I'm looking at a lot of audio-related stuff at the moment: Emulated speech in the Sega Vector games, analog sound circuit simulation, sound in Gorf and the Astrocade Games, other security chips, etc. I'd also like to work on some kind of simulation for the pre-CPU games, (There are a lot of them), in MAME, and add some obscure consoles to MESS. I just wish it was my full-time job.

4. What initially motivated you to put the Slapstic into the "goal" box? Was it a particular game?

Well, it was curiousity for me, initially. I started off just investigating a little bit with Empire Strikes Back, then got distracted. Later, Aaron Giles proposed that he'd write the Atari System 1 drivers while I worked on the slapstic chips that went into those games. At the time, this was a great division of labor because I could really concentrate on the hardware.

5. Were there any previous (hardware/software) attempts to beat the slapstic?

Yes. Cliff Koch actually made a "replacement chip" for collectors who wanted to convert their Star Wars into an Empire Strikes Back. This acted pretty much like the slapstic chip used in ESB. Also, The Gauntlet I and II slapstics had been figured out enough to create the hacked ROMs for Gauntlet and Gauntlet II. This alleviated the need for those slapstics for collectors, and allowed MAME and Neill Cortlett's Gauntlet emulator to work for those games. Finally, I think there was another unreleased emulator out there that had made progress on ESB.
I think most people were concentrating more on "how to beat it" rather than on "how they work". Subtle difference, but because MAME is meant as documentation, and we had multiple games to worry about, that's the approach we took.

6. Had anyone in MAMEDEV attempted to break the slapstic, or emulate other games that were poised by this in some form or another?

Not really. There was some work done on ESB by Steve Baines, and Aaron started on the System 1 stuff before I got involved, but that was about it.

7. From what had been told, this dreaded chip was a major wall to emulator authors. What approach did you use to solve the puzzle?

It was a team approach. Aaron worked on the driver software, along with reverse-engineering the game code whenever necessary. I built up a special fixture for interrogating the chips, and wrote some code to do that with a 68HC11 board. Between the two of us, and a steady supply of chips from others, it all came together. And now that it's in the MAME code, the info is available to any other emulators that want to use it.

8. So the 68HC11, I've had my share of experience programming with a development board with this microcontroller in it, and I can say it's excellent. For our readers, can you tell us what it is, what it can do and how can someone go about getting one?

Well, it's basically a single-board computer. It's CPU is a Motorola 68HC11 chip, which you can program in assembly or C. Among other features, It has a serial port to connect to PC or Mac, and a bunch of pins you can control via software. If you write up the appropriate software for it, and build an adapter for the item you're testing, it can be very powerful. I've used it to read non-standard ROMS, slapstic cracking, etc. I got my original one long ago as a "leftover" from a school project. I recently bought another from Motorola, when they were running a promotional special through one of their a distributors. It should be on their web site.

9. How did you get your hands on those Slapstic chips? Are Slapstics different each one from the other, or are they basically the same chip in all the games?

Several collectors on the MAME team sent me chips. Aaron even delivered one in person, while on vacation. Are they all different? - good question. We didn't know the answer to this one at first. We new that some games use the same exact chips, and we also new some couldn't be interchanged. We eventually determined that they all do basically the same thing...but they use different addresses as "keys" depending on the part number. Guessing, or scanning the chips is the only way to get the keys.

10. How long since the development started until you got the first slapstic game to work? How were the attempts? Did the game drivers worked preliminary or was it an all or nothing deal?

I think it was a few months, give or take. Some of the drivers worked preliminarily without any slapstic emulation, but they'd mess up sooner or later. As it turns out, the Gauntlet games only access the more advanced features of the chip on later levels, so they started to work right away. I remember I thought we were done a little too early :)

11. What was the first game that made it through?

Well, even though the Gauntlet's were working ok, we knew that the other games used "the rest" of the slapstic functionality right away, because they were basically broken. I had been querying the Marble Madness slapstic, and the latest code I sent to Aaron still wasn't working. Then, Aaron noticed a code segment in the Marble Madness game code which hinted that maybe he should try to tweak the slapstic code a bit (a one-line change). Marble Madness worked flawlessly! Based on that, we knew how they all worked.

12. You must feel very proud to have "The cracking on the slapstic" on your back. What do you think were the major factors that helped this come true?

Well, working with the MAME team is excellent. The team has people of many different talents. It would have taken me forever to do what Aaron did, for example. And without the chips I couldn't have done anything. We had the software talent, hardware talent, and parts, and the emulator framework.

13. Are there still things about the slapstic that remain uncovered?

Well, a bit. We've still got the bugs in the Gauntlet games to be fixed, and of course there's still the Empire Strikes Back, and some others. But, I believe it's only a matter of getting the right keys, not of understanding.

14. What is your next Mt. Everest? Is there something now as dreaded as the Slapstic was?

Nothing really stands out at the moment. A lot of the current "security-chip" and "encryption" challenges revolve around more modern games, which don't hold quite the same charm for me. (although I'm sure I'll end up involved if I can help.) Seems like you never know when the next Everest will show up, though. At least I usually don't dread it when it does :)

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