Complex sentence: ANSI.SYS and similar drivers continued to work in Windows 9x up to Windows Me, and in NT-derived systems for 16-bit legacy programs executing under the NTVDM.
Split into simpler sentences: ANSI.SYS and similar drivers continued to work in Windows 9x up to Windows Me. ANSI.SYS also works in NT-derived systems for 16-bit legacy programs executing under the NTVDM.