Even on the Atari ST you would use a "RAM disk" when working with "large" data before manually flushing it to a floppy. Some people would use the trashcan icon

Even on the Atari ST you would use a "RAM disk" when working with "large" data before manually flushing it to a floppy. Some people would use the trashcan icon to emphasise the need to manually flush... Not quite a cache, but the concept was there.