Some rather brain dead BIOSes use "33 C0" at the beginning of the MBR as a magic number for a "modern" MBR. This is a relic of how all Windows NT-family MBRs begin with "33 C0", while no DOS or Windows 9x MBRs do.
Without this magic value, the affected BIOSes will enable DOS/Win9x-specific workarounds, mostly in relation to drive access, which tend to break large disk access or LBA in newer MBRs.
Some rather brain dead BIOSes use "33 C0" at the beginning of the MBR as a magic number for a "modern" MBR. This is a relic of how all Windows NT-family MBRs begin with "33 C0", while no DOS or Windows 9x MBRs do.
Without this magic value, the affected BIOSes will enable DOS/Win9x-specific workarounds, mostly in relation to drive access, which tend to break large disk access or LBA in newer MBRs.