"Disk drives and hard disks are easily accessible through a very high-speed DMA channel linked to both the floppy disk and hard disk ports" is from the glossy released from Atari. From your comment and this, I am definately now confused...
The Atari Historical Society states 1.33Mbps in their technical specifications. This is the resource that I used. But, reading the original material, I noted that you are correct, it should be MB/s.