Linux has /dev/shm a shared memory ram disk by default. You can create a ram disk on a mac with diskutil erasevolume HFS+ 'ramdisk' `hdiutil attach -nomount

Linux has /dev/shm a shared memory ram disk by default. You can create a ram disk on a mac with diskutil erasevolume HFS+ 'ramdisk' `hdiutil attach -nomount ram://8388608` Though I have not seen a mac with more than 32gb ram. There are paid applications for creating a ramdisk in Microsoft Windows. Some of them will even sync back to disk based for you and read from disk back into ram on startup.