The unnamed studio told Wii U Daily that the next generation system will be powered by a quad-core 3GHz PowerPC-based 45nm CPU.
It went on to say that the Wii U also includes 768 MB of DRAM "embedded" with the CPU, and shared between CPU and GPU, as well as 40nm ATI-based GPU.
Nintendo is allegedly testing two versions of the console, one with 768 MB of DRAM, and another with 1GB. This DRAM is said to be embedded with the processor.
The anonymous developer claims that it is in the process of porting a PlayStation 3 game to the Wii U. The title in question was not divulged.
Earlier this week, Nintendo of America boss Reggie Fils-Aime said that the Wii and the Wii U will "co-exist for some time".