This was unique to Commodore. They owned MOS which made the chips so it was not as costly for them to do this. Honestly it sucked longer term because there was

This was unique to Commodore. They owned MOS which made the chips so it was not as costly for them to do this. Honestly it sucked longer term because there was no way to really upgrade how the filesystem DOS worked unlike on the Apple or the Atari. It was cool however because there were tools that offloaded things to the drive CPU. You could also write programs for copying disk that you loaded into the RAM on the drive and then disconnected them from the computer. You used the drive lights to tell you when to swap the disk.