More on the way!

Update 14 August 2025: More units expected to be available the week of August 25. Waiting on the 26-pin connectors for VERA to arrive.

Update 5 August 2025: Sold out? More kits are being assembled daily. Please be patient and join the waitlist to be notified as they come available.

Update 4 August 2025: Approximately 25 kits have now been assembled and will be made available here within the next day. This is far less than the number of people on the waitlist but as an individual putting these together, I will have to release these in batches based on the number that I can produce. If these appear sold out again, please keep yourself on the waitlist. I will continue making kits until the waitlist is empty for 7 days. It may take a bit, but I am committed to providing a kit to all interested buyers.

Bonus: The RAM expansion module boards will arrive today! I made a risk buy of a bulk quantity of these so that if they pass verification testing this evening, they will be immediately available for purchase with OtterX kits tomorrow. These new RAM expansion modules are designed to fix the cartridge clearance problem of the first run OtterX boards and shown in Ken's video review.

New Version 1.5!

After 18 months of feedback from customers all over the world, the OtterX design has been updated to reduce build errors and improve functionality. Read below for a list of the design updates.

OtterX

For those looking for a DIY 8-bit computer with huge capabilities and a large community supporting it, the OtterX is an all-through hole, Commander X16-compatible, ITX form factor, 8-bit retro computer kit with an adorable Otter mascot for the industrious retro enthusiast!

OSHW Certified!

OtterX is now certified by the Open Source Hardware Association. OSHW #US002763

The kit

This kit contains all through-hole components and ports for mounting to the PCB. All boards with surface mount components come pre-assembled and tested, including: "VERA" video board; OPM2151 "chiplet" drop-in replacement for the Yamaha YM2151; and I2S DAC replacement for Yamaha YM3012.

Key features:

• 8MHz W65C02
• W65C816 drop-in ready
• Compact, Mini-ITX form factor
• 40K low RAM
• 512K banked high RAM
• 512K ROM
• Silkscreen labeling designed to ease assembly
• Informative/Educational PCB design with detailed silkscreen
• "Commander X16" Compatible
• 2x SNES-compatible controller ports
• Header for legacy IEC-compatible serial/disk port
• Stable overclock to 10MHz with 20MHz user-supplied oscillator
• YM2151 clock stretch disable jumper
• Real-time clock with battery backup
• I2C Grove Connector

Assembly time: approximately 5 hours, depending on experience and soldering equipment.

Version 1.5 improvements

The board for sale here is the new OtterX 1.5 design which has the following changes:

• No more "bodge board". Cartridges work flawlessly on this board design without needing a special board and bodge wires.
• IEC port removed. The IEC port was used by less than 5% of customers and its location put it in conflict with the upcoming digital video output board. A 6 pin IDC-style box header is provided to allow a passive connection to an IEC "dongle" to add this functionality back in.
• TO-92 transistor footprints changed to new footprint with wider spacing. Microscopic solder bridges between transistor pins was the #1 cause of build issues with the original OtterX. This change should remove this issue entirely.
• NES 3&4 ports have moved to a 6-pin IDC-style box header. A "dongle" to make these easily available is coming soon.
• TVS diode footprints have been corrected so that bidirectional or unidirectional ESD protection diodes will work.
• Cartridges with a shell now fit the card edge connector without conflicting with the memory expansion module.
• Memory expansion module has been redesigned to provide space for cartridges and a standoff to ensure that the memory expansion doesn't short contacts against the battery clip below it.

Not included:

NOT INCLUDED: PS/2 keyboard, VGA monitor, ATX power supply, and PS/2 mouse (optional).

ATX power supply options are available as an order option.