From Wikipedia:

The SuperCPU is a processor upgrade for the Commodore 64 and Commodore 128 personal computer platforms. The SuperCPU uses the W65C816S 8/16 bit microprocessor.

It was developed by Creative Micro Designs, Inc and released on May 4, 1997.

It used a device called the RamCard to increase its capabilities. The card is no longer sold by Creative Micro Designs as of 2001; the distribution was taken over from 2001 to 2009 by the U.S. company Click Here Software Co., but it is unclear if any were manufactured after 2001.

The unit can have up to 16 MB RAM installed. The unit supported a "Turbo" switch which, when enabled, clocked a Commodore 64 or Commodore 128 up to 20 MHz. The unit plugs into the expansion port of the computer. The unit uses 0.4 A (400mA) and shadow ROM in 128 KB of RAM. Internal ROM was 128 KB. Using the RamCard (SuperCard), fast page mode (FPM) not EDO memory modules with PS/2-SIMM socket can be used in the capacities of 1, 4, 8 or 16 MB.