PrimoCache (formerly called FancyCache) is a very useful Cache Disk program, developed by Romex Software from China. As opposed to virtual memory, it virtualizes the idle space of physical memory, SSD hard drive, or flash drive on your computer into the cache space of your HDD hard drive, making your computer run faster. In other words, it can store the data that needs to be read frequently in the hard disk into a faster storage device such as physical memory, thus effectively improving the performance of the physical hard drive.

There are many ways to fake the displayed capacity info of any type of storage device (this is nothing new in the Chinese electronic marketplaces, where you have to have a third eye to avoid being cheated). For example, using the "subst" command to create a partition shortcut (which can be understood as a virtual partition); using "SFDISK" (hard disk partitioning tool under DOS) to modify the partition table information; using WinHex (to offset the DBR of disk to the target capacity), PC-3000 and similar tools to change disk information in the underlying hardware.