IBM PC's, even with an 8088 (wow!) used a DMA controller for floppy disk because of the data rates. You could just about code a floppy read loop for an i8272 with interrupts disabled on a 4.77Mhz CPU. My first PC had an 8089 IOP to do the DMA!
Notice how the macintoshes grind to a halt when doing any reading or writing to a floppy and the cursor starts being sluggish.