Besides its 128 MB of Flash ROM, "The!Cart" has a built-in 512 KB RAM chip. This chip was required because the physical bank size of the Flash chip is 64 KB, i.e., only complete 64 KB blocks can be erased. So without the built-in RAM, a standard Atari 48 KB or 64 KB computer would not have been able to update "The!Cart". Using the built-in RAM of "The!Cart" for other purposes has always been on the long to-do list, but time did not allow me to pursue that aim.
Luckily, in 2019, my fellow Atarian Holger Janz received his "The!Cart" and found writing a RAM disk driver encouraging. He likes to use real hardware and actual programming cartridges, and we all know that having a RAM disk there is a handy thing. He first went into the details of DOS 2.5 and its existing RAM disk implementation and released it to the public after some weeks. Support for other DOS versions is planned.
The video below shows how The!RamDisk can be used. The detailed documentation of The!RamDisk, including ready-to-use disk images, source code, and test programs, are available at https://github.com/HolgerJanz. You can follow the development, ask questions, and give feedback via the ABBUC thread (German) or the AtariAge thread (English).