Favourite System 80 DOS
NewDos/80 V 2.0

Favourite Dos? Actually, it was the ONLY '80s Dos I knew but it worked for me. Once I got my head around the PDRIVE parameter that is (-:
Powerful and customisable, this DOS won favour with a lot of System 80 users, who often sported a mixture of different drives on their system.
I became very familiar with LMOFFSET once I acquired a disk-based System. I had a lot of cassette-based programs to convert.
The DOS is available on the Disk Image Archive, where brave souls can also download the manual.