Many hard drive controllers had a crude low level format program in their ROMs. With DEBUG, you could JMP to it, typically G=C800:5 although some were C800:0 or other offsets. U C800:0 to look at the code and find it.
G=C800:5 or G_c800:800 for Western Digital controllers G=C800:CCC for Adaptec controllers. G=C800:5 for DTC (Data Technonolgy) controllers G=C800:6 for OMTI controllers
according to https://kb.iu.edu/d/aaoa
