1541 wrote on 2021-10-19, 20:42:

Some programs are said to have issues when the MSDOS.SYS is smaller than 1024 bytes (which is the case with the 7.1 delivered version.)

That's why Win9x adds comment lines to MSDOS.SYS to make it >1024 bytes.

My NU.EXE from Norton Utilities 4.5 Advanced Edition refuse direct hard disk access without using the command LOCK in DOS 7.