geoRAM

During the chip shortages of the 1980s, Commodore could not produce enough of its RAM Expansion Units (they eventually cancelled them). The GEOS operating system relied heavily on extra RAM and so the company behind GEOS produced their own memory expansion cartridge, called the geoRAM.

Using a mapped-in page scheme, the geoRAM was much slower in operation than the DMA-driven REU cartridges; hence, not much software other than GEOS actually supported it.