
This is an Entirely New and Unique Expansion System for the 576NUC+...
In order to put all these features into one package, it required tossing out a few prior upgrades that came before (e.g.; Physical Cart/Fujinet, stand-alone SDrive, stand-alone FujiNet). However this system brings improved versions of all of that, replacing the Physical Cart with a built-in 16MB Flash Ram Multi-Cart, and adds a Real Time Clock, while also continuing to support either type of drive. For both the FujiNet and the A8PicoCart a more standardized USB-C connection has been established. And specifically where FujiNet firmware flashing is concerned, an FTDI-232 USB to Serial interface has been implemented that is built-in to all modern operating systems. This entire system is based upon Public Domain and/or Open Source information and design releases, without any proprietary firmware or hardware required.
Essentially this takes it back to the originally intended fully portable and miniaturized system envisioned as a "toss it in a bag & take it with you" minimalist design. Making it the ultimate solution for meet-ups and game parties.
The time has finally come to leave your physical ROM carts at home.
Don't Lose your Cool...
An optional but highly recommended Fan and Shroud cooling system is available to keep all those stacked boards from overheating. This is specifically an active forced air cooling system that spins up whenever the 576NUC+ is switched on. And while it's working hard to cool down the chips, the fan remains whisper quiet, being hardly noticeable.
This protects and lengthens the life of your investment, and especially helps preserve the expensive and sometimes rare 40+ year old Atari VSLI chips. Because we all know that Pokeys are getting quite expensive and becoming very difficult to find.
The fan is a Noctua 40mm x 40mm x 10mm 5VDC muffin fan which comes with all the necessary hardware and cabling, and an STL for the shroud is available as a free download down below.
The Noctua Fan can be purchased from Amazon.
There be Programmable Devices in here...
There are 7 programmable devices in total that require flashing as part of this complex expansion system if you plan on taking this on as a DIY project.
- EMMU (Microchip/Atmel ATF22V10C-15PU PLD) - can be removed from the 576NUC+, reflashed, and then moved to the NUCplus4
- TKNUC1MB embedded in the 576NUC+ (Microchip PIC16F1847 MCU) - flashed via ICSP
- TKNUCSD a PS/2 command sub-processor (Microchip PIC12F629 MCU) - out of socket flash
- TKNUCFN a PS/2 command sub-processor (Microchip PIC12F629 MCU) - out of socket flash
- SDrive-ng an SD to SIO processor (Microchip ATMEGA328P MCU) - out of socket flash with future SD Card updates
- FujiNet WiFi networking (Espressif Systems ESP32-WROVER-E-N16R8) - embedded USB-C FTDI serial flash & logging
- A8PicoCart a 16MB Multi-Cart processor (Ali-Express RP2040 TYPE-C 16MB Purple) - embedded USB-C flash
Two dedicated chip programmers will generally be required to complete this task: TL866II Plus and a Microchip PICkit (or JOY2PIC), and one USB-C to USB-A male to male cable for the last two items (or if your PC or MAC has USB-C ports then a USB-C to USB-C male to male cable will work).
There's a New Case in Town...
Once again due to physical changes associated with this new daughter board, a customized version of AtariAge member Mr Robot's original XE type case had to be created. This time around we gave it a cool XE style badge to really show off its heritage.
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TBA Ordering Info
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Latest 2025 NUCplus4 Version as Complete Assembly
(MIDI Synth and MIDI PIC chip are Optional)
(MIDI Synth and MIDI PIC chip are Optional)

Build It / Flash It / Use It
MAJOR REVISIONS to all of the files took place in March 2025 - DownLoad the NEW Files Below
Since this is an ALL NEW VERSION of the NUCplus4 be sure to check out the NEW datasheet
Note: V1.6 Main PCB and V1.4 FujiNet only PCB are still usable after firmware updates
--- Consult this BLOG Post for Assembly Notes ---
Since this is an ALL NEW VERSION of the NUCplus4 be sure to check out the NEW datasheet
Note: V1.6 Main PCB and V1.4 FujiNet only PCB are still usable after firmware updates
--- Consult this BLOG Post for Assembly Notes ---
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NUCplus4 MAIN Daughter PCB
2-Layer x 1.2 mm |
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Hi-Resolution Schematics (ALL)
Revised March 2025 |
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NUCplus4 FujiNet/MIDIplay PCB
2-Layer x1.6 mm |
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Bill of Materials (ALL)
Revised March 2025 |
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NUCplus4 Datasheet
Operating Specs |
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Firmware Flashing Files (ALL)
Revised March 2025 |