Corcomp’s 128k and 512k memory cards are basically only usable as RAMDISK these had no battery backup so power off=blank
Myarc’s 128k and 512k memory cards contain a DSR routine for RAMDISK, these had no battery backup etc..
Horizion RAMDISK is a dedicated ramdisk of battery-backed memory. It will survive a reboot/power down as long as your batteries are good. Various sizes were released getting bigger as ram prices dropped.
Fetzner Horizon RAMDISK is available now with all the redesigns and updates