Mercury turns MiSTer FPGA into the console it always wanted to be

MiSTer FPGA machines have a habit of growing cables. Start with a DE10-Nano, add USB, SDRAM, analogue video, storage and a few specialist extras, and the tidy little board can become a busy desk companion. Mercury takes a different route. It brings much of this hardware into one 16 × 14 × 5 cm case, giving MiSTer a cleaner console format without changing what sits at its core. This isn’t a replacement for the FPGA board itself. You’ll still need a Terasic DE10-Nano, or a Mister Pi setup with the required USB adapter, plus SDRAM where your chosen cores need it. Mercury supplies the surrounding hardware: I/O, USB expansion, analogue connections, internal storage options and extras usually handled by separate boards.

One box for the usual MiSTer extras

Mercury folds several common MiSTer add-ons into its mainboard. Its feature set covers functions comparable with the MiSTer I/O Board 9.2, a seven-port USB hub, a battery-backed real-time clock and ADC input.

The FPGA board mounts upside down inside the case, with USB, Ethernet, GPIO and the MicroSD extension connected internally. The finished machine ends up much closer to a conventional games console than the usual stack of exposed boards.

Dual SDRAM caters for heavier cores

Mercury supports dual SDRAM, a useful option for cores with higher memory demands. Saturn FPGA implementations are one obvious use case.

There is a trade-off. A dual-SDRAM setup removes access to Mercury’s analogue A/V outputs. Users who still want analogue video can use MiSTer’s HDMI direct-video route instead. Different setups can come with different connection choices, so the final configuration comes down to the cores and display hardware in use.

SSD storage can live inside the case

Mercury includes an internal USB connection for a SATA SSD used through a SATA-to-USB adapter. Large libraries can stay inside the enclosure rather than hanging from another cable. Internal USB isn’t limited to storage. An NFC reader can sit inside too, letting tags or stickers trigger games or software.

MT32-Pi gets its own place

Mercury has built-in support for MT32-Pi using a configured Raspberry Pi Zero 2 W. In supported computer cores, this can provide MT-32-style MIDI synthesis without leaving another board loose beside the console.

There’s a clever connection detail here. MT32-Pi normally uses MiSTer’s User I/O port, which can clash with hardware such as SNAC adapters. Mercury includes switching hardware so the User I/O connection can move between the internal MT32-Pi and the external port through console controls or an infrared remote. No reboot is required. The external User I/O connection supports SNAC and SNAX equipment, with level shifting handled on the board. DB9 SNAC8 setups can work through an optional adapter.

Analogue video gets plenty of attention

For video, Mercury keeps the familiar MiSTer VGA-style multi-output connector and adds compatibility with Sega Saturn RGB and S-Video cables. A switch lets users select different RGB sync arrangements.

The Saturn-style connection and the standard analogue multi-output aren’t intended for simultaneous use, so setup choice matters here. Audio comes through an integrated DAC and headphone amplifier. The front audio socket handles headphone output and tape input duties. Using both at once requires a standard headset-style splitter.

Controller charging works with the console switched off

Two front USB charging ports can charge wireless controllers when Mercury is switched off. They support controllers using more advanced charging negotiation, including DualSense and DualShock 4. Charging can stay active, remain disabled or be switched on only when needed, which suits a living-room setup where controllers often stay plugged in between sessions.

Remote control and active cooling round things off

Infrared remote support is built in, with programmable commands for system functions. Multifunction air-mouse receivers can work too, giving MiSTer keyboard and mouse input alongside separate infrared controls.

Cooling comes from a bottom-mounted intake fan aimed at the FPGA hardware. Mercury uses USB-C PD and calls for a 24 W or higher PD-compatible adapter for full operation. Lower-rated or non-PD supplies can limit internal extras such as the MT32-Pi and SSD.

Mercury doesn’t change what MiSTer FPGA is. It changes how a finished MiSTer can be packaged. For anyone piecing together analogue video, original-controller support, SSD storage, MIDI hardware and plenty of USB connections, the appeal is simple: fewer loose boards, fewer dangling adapters and a machine shaped more like a console from the start.