You can actually load MS-DOS and PC-DOS high on an XT, if you have a memory card that populates UMBs, but you need DOSMAX and a utility like USE!UMBS. It doesn

You can actually load MS-DOS and PC-DOS high on an XT, if you have a memory card that populates UMBs, but you need DOSMAX and a utility like USE!UMBS. It doesn't seem to work with FreeDOS though. I've been able to get like 605k conventional RAM with PC-DOS 2000 and still have big partitions. Practically speaking, even a 60Mb partition is slow to rattle though.