Hardware addons and modifications have a long history on C64 and C128. Shortly after the release of the C64 to the public the greatest public demand seemed to be faster loading systems. Companies therefore published several speed loaders and Epyx even had/has a trademark on 'Fast Load' in the USA. So called memory dumpers or freezers became popular a little later. Naturally when the industry protected newer game generations with better protections and loading systems to avoid piracy also the demand for better freezing systems raised. Kernel modifications are quite limited on space and the desire for a little more comfort made RAM and ROM based cartridges with multiple functions popular very quickly.
The following chart shows what current researches on these multi function carts (also referred to as 'SuperCarts' or simply 'Freezers') have yielded in regards of time and versioning. The listed carts are also the ones mainly exposed on this wiki.