Hi there. I've just purchased a Sega Teradrive model 3, which is currently in transit from overseas. I'm not just interested in this system for collectors value however. I want to document the precise level of interaction possible between the PC and the Mega Drive hardware. The most detailed information that is currently available is that they are "to some extent aware of each other". Depending on the level and method of interaction, the Teradrive has the potential to act as a hardware debugger. This could help to improve emulation for the Mega Drive. More accurate timing information could be sampled for the VDP graphics chipset for example, and it could help to make emulation for Virtua Racing a reality by providing the ability to probe/snoop on the SVP. I've spent years reverse-enginnering games for the Mega Drive, and I'm currently writing my own Mega Drive emulator, so I'm quite familiar with the Mega Drive platform. The PC side is a bit of a wildcard however. There's no way of knowing how difficult it will be to document the interface until I can run some tests on the system itself. If the interface proves to be less than obvious, disassembling and studying software written for the system will be the key to reverse-engineering the interface. To the point, the system I am being sent has some software loaded on it, but I won't know precisely what software is included or what it does until the system arrives. I do know however that none of the installation disks will be included. The more software I have access to, the easier this project will be, so in the interests of documenting the capabilities of this extremely enigmatic system, I'm asking for other Teradrive owners out there to share any software you have for the system. In particular, I would be extremely interested in any driver disks, and the game "Puzzle Construction". If you have access to a Teradrive with a HDD, or any installation disks for software written for the Teradrive, I'd very much like to hear from you. You can use a program called Winimage to easily take images of any installation disks. Winimage can also be used to take images of hard drives, although this does require physically removing the HDD from your Teradrive and attaching it to your computer. I'll be doing this myself to the HDD in my Teradrive when it arrives, so I'll be more than happy to provide step-by-step instructions for anyone who wants to do this. Even if you're not interested in sharing the data, you should take a backup of the HDD in your Teradrive at some point, because the drive won't last forever, and some software for this system will be a lot rarer than the hardware itself by this point. If you have Teradrive software or HDD images but you don't want to post them publically, please email me at nemesis1207@hotmail.com and we can discuss it in private.
The pc and megadrive and support components are fully integrated on the motherboard, you're in for a hard time for sure. You should have gotten the UK version, it's much more clearcut. It has less chips, is faster. Plus the components are easy to recognize. The Japanese model has so much more older support hardware on it and you'll probably destroy it taking it apart, it's a real nightmare inside. It's also only a 286. Most of the chips in mine have no real markings. The Uk version is reasonably modern, the Japanese model, positively primitive and reminiscent of an ibm model 8088 as it has an old ata1 pio hdd with a non standard connector for power. The FDD is similarly antiquated. You're going to need an old style bios battery, and a bunch of caps too. The battery is the type that is soldered to the board. It's probably leaked all over by now, I wound up removing the ones in my set and bagging them. Good luck.
I had no idea there was a UK version. All the information I found said it was released in Japan only. At any rate, the one I'm getting runs on 120V mains, so it'll be Japanese. The actual layout of the hardware isn't really an issue for my purposes though, as I'll be attacking this from a software side. I'm comfortable doing whatever repairs are necessary on the system. I've got an Amstrad MegaPC I had to replace the backup battery on too. The system is reportedly in working order however.
Japan is 100v, make sure you don't fry it. If you have a mega pc, why do you need a teradrive? ( I mean the mega pc as the uk version, btw)
The MegaPC is basically just a Mega Drive bolted on to the side of a PC. Apart from the FM chipset, the game card which contains all the hardware for the Mega Drive only draws power from the PC side, and operates completely independently from the PC hardware. Because of this, it is impossible to run software on the PC side which can interact with the Mega Drive hardware. This makes it of little practical use to someone interested in Mega Drive development, because it's not really any different than running a normal Mega Drive, and doesn't offer any benefit to a normal system, apart from a clean RGB video output. The Teradrive on the other hand is an integrated system, with apparently some degree of communiction possible between a normal piece of software running on the PC side, and the Mega Drive hardware itself. This opens up all kinds of possibilities, like running a program on the PC which can monitor the Mega Drive hardware while it is running. To a developer, this is gold. If the PC hardware can talk directly to the VDP for example, I can send test commands directly to the VDP and view the results, without having to go through the process of compiling a test rom, uploading it to a flash cart, and running it on the system. I can do ad-hoc tests of undocumented behaviour in seconds. More than that, it opens up the possibility to inspect the state of the hardware while the system is running, eg, dump the contents of the system RAM on demand. Basically, it's the difference between a devkit, and a PC with a Mega Drive sitting on top of it. For a collector, the MegaPC may seem to be the better system. For a developer, the MegaPC doesn't mean much, but the Teradrive could be the holy grail. That's what I want to figure out: just how useful the Teradrive is to a developer.
This brings back memories from the Amiga 500 days. If you're not into Amiga, the Amiga 500 had the NMI signal available on the expansion slot, so that the Action Replay had full control. It would be fantastic if the PC-side of the Teradrive could trigger a NMI when the MD is in 68k mode and get control of the IP with full memory access. It is something like this you are hoping for, right? CF
I'll be happy with any level of interaction that can be put to some practical use. Rather than an interrupt-based hook though, Ideally I'd like to be able to do a transparent peek or poke into the 68000 memory map from the PC side, with no visible side-effects to the 68000, except perhaps a minor impact on timing when it briefly loses control of the bus. That would be the best. I don't know that it'll go quite that far, but I can hope.
I thought that the Teradrive had no interaction between the PC and the Mega Drive, much like the Mega PC (which, shockingly, was also a pile of crap - I had one as my first computer and sold it because the PC part is completely unupgradable).
I wish you luck Nemesis. I've always been interested in the Terra Drive so keep us updated when it arrives. Wont you have problems with the fact everything will be in Japanese?
Well, I do have a teradrive with a hdd. God knows if it is still functional, but I can dump it once you pull yours and figure out how to get a modern pc to read it without killing it.
I own model 2 (2 fdd, no hdd), just the computer itself and teradrive monitor. I would love to know what is the geometry of the 30MB PIO 1 IDE hdd was. I hope that may be I can partition a large compact-flash card with this geometry and it'll get detected by teradrive. Assembler, if you can please take a photo of HDD, it'll be really cool!
