Analogue’s Mega Sg remains one of the more interesting niche products we’ve reviewed in the last little while, but one thing it couldn’t do was play Sega CD games on its own. As we mentioned in the Mega Sg review, this hardware is all pushing 30 years old, and failures are bound to happen. What’s a
lag snob retro purist to do? Today on its live YouTube stream, Terraonion announced one possible answer: the MegaSD, an FGPA-based cartridge that not only plays Genesis and Master System games with full FM audio support, but Sega CD games as well.
Terraonion is already widely known for its line of NeoSD cartridges that play in NeoGeo MVS (arcade) and AES (home console) systems and the Super SD System 3 (SSDS3) which emulates the PC Engine and TurboGrafx-16’s CD add-on with an FPGA. The SSDS3 is closer to the MegaSD, since both add-ons replace the original consoles’ optical add-on with an SD card reading ISO images and playing them back on original hardware. Several retro YouTubers have gotten their hands on the hardware early and have nice things to say. Bob from RetroRGB says on Twitter that the cartridge pulls less power than the original Virtua Racing cartridge for the Genesis and shouldn’t put any undue strain on your vintage hardware.
The Sega CD is a beefier beast than the PC Engine Super CD drive. Sega’s add-on boasts a second Motorola 68000 CPU and a custom video display processor (VDP) from Sega. These extra processors have been emulated in FPGA to work on the Mega Sg as well as original hardware, including the Genesis 3 (which can’t interface with the Sega CD) and the ill-fated Genesis Nomad handheld. The Nomad does require some minor modifications to connect analog audio from the cartridge, however.
The MegaSD works with these previously-incompatible systems because it connects to the console via the cartridge slot, not the side connector normally reserved for the Sega CD. One downside to Terraonion’s approach of using the cartridge slot instead of the extension port on the side of the console is that the six games that use both the Sega CD and the 32X will not work since the 32X hardware blocks access to the CD bits in the cartridge slot. However, Terraonion promises that this can be fixed with a passive adapter that lets the cartridge run from the expansion port, and will produce one if there’s enough interest.
Terraonion’s SSDS3 was mired in a little controversy because both the RGB video and analog audio output from the system were marred by noise, and when confronted about it, Terraonion initially refused to acknowledge the issue. The retro modding community stepped up with a pair of fixes: a video board designed by Voultar and an upgraded audio amp created by FirebrandX. Both of those projects were released as open-source designs, and some industrious modders offer modification services for one or both of these mods. Terraonion later fixed these issues in its Revision B hardware and directly addressed the SSDS3 in today’s video. The company says that not only did it learn from those mistakes, but hired on FirebrandX to help design the cartridge audio connector for the MegaSD. Since the Sega CD didn’t output video directly, analog noise in video isn’t an issue. With any luck, this device will come out of the gate sans controversy.
The most surprising thing to come out of Terraonion’s announcement is that the MegaSD will be ready to go very soon. Terraonion’s web shop lists the MegaSD at a hair-raising €232 and €18 shipping to the USA. The company says the MegaSD will start shipping in early August. That’s around $280 US at current exchange rates. When compared with the $180 Mega Everdrive X7, which will play Master System games but not Sega CD games, Terraonion’s optical emulator delivers additional value for less than the cost of a used Sega CD on eBay. I’m currently scrounging around in the couch cushions to see what I can dig up.