A SNES, Ray Tracing

December 17, 2020 by Jenny List 8 Comments

A trick famously used by Nintendo to keep its slowly aging SNES console fresh against newer competition was to produce new games with extra support chips in the cartridge to push out hitherto-unthinkable performance. Chips such as the famous SuperFX gave us 3D polygonal graphics, but it would have been a few more years before even much faster platforms could achieve real-time ray-tracing. Nintendo may not have managed it, but here in 2020 [Ben Carter] has a SNES on his bench rendering a complex 3D ray-traced world.

Ray tracing refers to the practice of rendering a scene with accurate lighting by tracing the rays of light that go towards making each pixel. It can achieve results that even approach photorealism, but it remains an extremely computationally intensive job for any computer. To do this with a SNES he hasn’t resorted to a modern computer like the excellent Raspberry-Pi-based NES DOOM cartridge, instead he’s tried to create something that might have graced a Nintendo custom chip back in the 1990s. The tool may be a thoroughly modern DE10-Nano FPGA dev board, but what it implements could conceivably have been made as a 1990s-spec ASIC. In it are three ray tracing cores that do the work, but the final rendering is handled by the SNES itself. At 200 x 160 pixels and 256 colours it’s no graphical powerhouse, but the maximum frame rate of 30 fps makes it no slouch for the day. The video below the break supplies extra detail.

Perhaps an unexpected takeaway of the rendered scene lies in how of its era it seems. It comes from an age in which checker-board floors, mirrored balls, and azure blue skies looked so futuristic, and just before the likes of Toy Story redefined what the general public might expect from 3D rendering. If Nintendo had produced a ray-traced SNES game using a chip like this one, it would have certainly been a defining moment for gaming in that decade.

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A Straightforward Guide To Unlocking The Nintendo Game And Watch

December 2, 2020 by Jenny List 15 Comments

Nintendo’s reborn tiny handheld game has certainly attracted the attention of hardware hackers, and we’ve been treated to a succession of exploits as its secrets have been one by one unlocked. With relatively straightforward hardware it conceals potential far beyond a simple Mario game or two, and it’s now at the stage of having a path to dumping both its SPI Flash and internal Flash, unlocking its processor, and running arbitrary code. The process of unlocking it is now atraightforward enough to warrant a HOWTO video, to which [stacksmashing] has treated us. It’s early days and this is still touted as for developers rather than gamers, but it serves to show where work on this console is going.

The console’s STM32 architecture means that programming hardware is straightforward enough to find, though we’re cautioned against using the cheap AliExpress type we might use with a Blue Pill or similar. Instead the snap-off programmer that comes with an STM Nucleo board is a safer choice that many people are likely to have already.

The relative simplicity of the process as seen in the video below must conceal an immense amount of work from multiple people. It’s a succession of scripts to sequentially unlock and back up the various firmwares with STM payloads for each step. Finally the STM32 itself is unlocked, and the backed-up Nintendo firmware can be returned to the device or instead a custom firmware can be created. Aside from the DOOM we’ve already seen there are work-in-progress NES and Game Boy emulators, and fascinatingly also work on bare-metal games.

Given the lack of custom chips in this console it is easily possible that its hardware could be directly cloned and that Nintendo might have unintentionally created a new general purpose hacker’s handheld gaming platform. There are a few hardware works-in-progress such as increasing the SPI Flash size and finding the unconnected USB pins, so we look forward to more exciting news from this quarter.

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DOOM Running On The Nintendo Game & Watch

November 22, 2020 by Mike Szczys 14 Comments

Today the newly-released Nintendo Game & Watch can play DOOM. Sure, there are caveats…this is a watered down version due to the restraints of the hardware itself. But the important thing is that this shows the hardware has been fully owned. This is code written to replace the firmware that ships on the STM32 within, and that makes this a gorgeous little hardware platform that is completely open to homebrew hacking.

Honestly, you had to assume this was going to happen pretty quickly considering the effort being thrown into it. We first reported on Tuesday that the EEPROM memory which stores the ROMs on the Game and Watch had been decoded. Shortly after that was published, [stacksmashing] and [Konrad Beckmann] were showing test patterns on the display and mentioning the audio was working as well. Turns out they were able to dump the stock firmware despite the chip being security locked.

We’ll have to wait for more details on exactly how to dump firmware, but [stacksmashing] drops enough of a mention in the video below to confirm the obvious. A common approach to dumping code from a locked microcontroller is to find a vulnerability that grants execution of custom code. Being able to run just a few lines of your own code is enough set up something as simple as looping through all internal flash memory addresses and dumping them over a few GPIO pins. In this case our two heroes discovered some ARM code was being loaded from the EEPROM onto the STM32, and managed to inject their own directives to perform the dump. They have promised full details soon.

What we have today is a pretty tricky hack not just to load code, but to get DOOM to run on meager hardware specs. Notably, 128 k of SRAM and 1.3 MB of external RAM. There’s also a bottleneck with the 1.1 MB of FLASH for storing game files. The textures were stripped down, and memory allocation was rewritten, but the proof of concept is there and the game runs. Homebrew, here we come!

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Reverse Engineering A PokeWalker

November 21, 2020 by Matthew Carlson 16 Comments

The PokeWalker is part of Nintendo’s long quest to get children (and likely some adults) walking and exercising. There’s the PokeWalker, Pokemon Pikachu, PokeBall Plus, Pokemon Pikachu 2, Pokemon mini, and of course Pokemon Go. Despite being out a decade, there wasn’t a ROM dump for the device and there was minimal documentation on the communication protocol. [Dmitry Grinberg] took it upon himself to change all that and crack the PokeWalker open.

At its heart, the PokeWalker is just a pedometer with an IR port and a 96×64 grayscale screen. It came out in 2009 to accompany the new Pokemon release for the Nintendo DS. Cracking open the device revealed a 64KB EEPROM, a Renesas H8/38606R CPU, a Bosch BMA150 accelerometer, and a generic IR transceiver. The CPU is particularly interesting as in addition to being quite rare, it has a mix of 8, 16, and 32 bits with 24-bit pointers. This gives it a 64K address space. While the CPU is programmable, any attempt to do so erases the onboard flash. The communication protocol packets have an 8-bit header that precedes each packet. The header has a checksum, a command byte, and four bytes of session id, and an unused byte. Curiously enough, every byte is XOR’d with 0xAA before being broadcast.

One command is an EEPROM write, which uses back-referencing compression. Each chunk of data to be written is packaged into 128-byte chunks, though 128 bytes likely won’t be sent thanks to the compression. The command can theoretically reference 4k bytes back, but in practice, it can only reference 256 bytes back. It was this command that laid the foundation for the exploit. By carefully crafting the command to send, the command can overflow the decompression buffer and into executable code. Only a few bytes can be overflowed so the payload needs to be carefully crafted. This allowed for an exploit that reads the system ROM and broadcasts it out the IR port. Only 22k bytes can be dumped before the watchdog reboots the device. By changing the starting address, it was easy to do multiple passes.

After the ROM was stitched together from the different passes, the different IR commands were analyzed. In particular, a command was found that allows direct writes into RAM. This makes for a much easier exploit as you can write your exploit, then override a pointer in the event table, then have the exploit revert the event table once the system naturally jumps to your exploit.

[Dmitry] finishes off this amazing exploit by writing a PalmOS app to dump the ROM from a PokeWalker as well as modify the system state. PalmOS was chosen as it is an easy and cheap way to have a programmable IR transciever. All in all, a gorgeous hack with a meticulous writeup. This isn’t the first video game accessory that’s been reverse engineered with a scrupulous writeup, and we’re sure it won’t be the last.

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Exploring The New Super Mario Game & Watch

November 17, 2020 by Tom Nardi 26 Comments

Nintendo has revived the classic Game & Watch, this time in glorious full-color and running the same Super Mario Bros that first graced the Nintendo Entertainment System (NES) back in 1985. Even though it’s only been on the market for a few days, [stacksmashing] has already made some impressive progress towards unlocking the full potential of this $50 retro handheld.

It will come as no surprise to the average Hackaday reader that what we’re looking at here is a pocket-sized NES emulator, but until [stacksmashing] cracked his open, nobody was quite sure what kind of hardware is was running on. Thankfully there wasn’t an epoxy blob in sight, and all of the chips were easily identifiable. Armed with the knowledge that the Game & Watch is running on a STM32H7B0 microcontroller with a nearby SPI flash chip holding the firmware, it was just a matter of figuring out how the software worked.

It didn’t take long to find that an unpopulated header on the board would give him access to the Serial Wire Debug (SWD) interface of the STM32, though unfortunately he found that the chip’s security mode was enabled and he couldn’t dump the firmware.

But he was able to dump the RAM through SWD, which allowed him to identify where the Super Mario Bros NES ROM lived. By connecting the SPI flash chip to a reader and comparing its contents with what the system had in RAM, [stacksmashing] was able to figure out the XOR encryption scheme and come up with a tool that will allow you to insert a modified ROM into an image that can be successfully flashed to the chip.

So does that mean you can put whatever NES ROM you want on the new Game & Watch? Unfortunately, we’re not quite there yet. The emulator running on the device has a few odd quirks, and it will take some additional coaxing before its ready to run Contra. But we’ve seen enough of these devices get hacked to know that it’s just a matter of time.

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Dumping A N64 Development Cartridge Safely

November 2, 2020 by Lewin Day 8 Comments

Retro gaming enthusiasts have always had great interest in rarities outside the usual commercial titles. Whether they be early betas, review copies, or even near-complete versions of games that never made it to release, these finds can be inordinately valuable. [Modern Vintage Gamer] recently came across a pre-release version of Turok 3 for the Nintendo 64, and set about dumping and preserving the find. (Video, embedded below.)

With one-off cartridges like these, it’s important to take the utmost care in order to preserve the data onboard. Simply slapping it into a regular console might boot up the game, but carries with it a non-zero chance of damaging the cart. Instead, the first step taken was to dump the cart for archival purposes. When working with a prototype cart, commodity dumpers like the Retrode aren’t sufficient to do the job. [Modern Vintage Gamer] notes that a Doctor V64 or Gameshark with a parallel port could work, but elects to use a more modern solution in the form of the Ultrasave and 64drive.

With the cartridge backed up and duplicated onto the 64drive, the code can be run on a real console without risk of damage to the original. At first glance, the game appears similar to the final retail version. Analysis of the dump using a file comparison tool suggests that the only differences between the “80% Complete” ROM and the retail edition are headers, leading [Modern Vintage Gamer] to surmise that the game may have been rushed to release.

While in this case the dump didn’t net an amazing rare version of a retro game, [Modern Vintage Gamer] does a great job of explaining the how and why of the process of preserving a vintage cartridge. We look forward to the next rare drop that shakes up the retro world; we’ve seen efforts on Capcom arcade boards net great results. Video after the break.

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N64 Power Adapter Works Around The World

October 29, 2020 by Lewin Day 6 Comments

Modern electronics such as phone and laptop chargers are pretty versatile no matter where you find yourself in the world. Capable of running off anything from 100-250V, all you need is a socket adaptor and you’re good to go. Video game consoles of the 1990s weren’t so flexible however. [MattKC] was tired of messing around with step down transformers to run his US market N64, and decided to rectify this, building a universal adapter to run the console instead.

It’s a proper hacked build, assembled out of a jumble of old parts. An broken N64 power adapter was harvested for its case and unique DC plug, which carries 12V and 3.3V to the console. Few compact power supplies exist delivering this pair of voltages, so [MattKC] got creative. An old router was sourced for its 12V 2A supply, and was combined with a 3.3V buck converter to supply both rails. With some creative bodging and plenty of mounting tape, the supplies were crammed inside the original case and wired up to the original jack and a figure 8 cable, allowing easy socket changes in different countries without the use of ugly adapters.

While few of us routinely travel with 25 year old Nintendo consoles, for those that do, the convenience of a single universal supply can’t be overstated. Fitting a step-down transformer into carry-on luggage simply isn’t practical, after all. We’ve featured similar hacks as far back as 2006, or more recently, a project seeking to rebuild a new PSU for the venerable Amiga 500. Video after the break.

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