https://github.com/PlummersSoftwareLLC/TinyRetroPad
https://github.com/PlummersSoftwareLLC/TinyRe … roPad/issues/21

Assumption is that it is only compatible with the later versions of Windows but I haven't tested.

A working, Notepad-style Windows text editor in roughly 2.5 KB. […]
Show full quote

A working, Notepad-style Windows text editor in roughly 2.5 KB.

Compiles with: MASM and Crinkler.

TinyRetroPad is a fork of Dave's Tiny Editor (DTE) by Matt Power, which is itself an extension of tiny.asm HelloAssembly by Dave Plummer. The original goal was a working windowed text editor in the sub-1KB category; TinyRetroPad keeps that minimalist, size-obsessed spirit while filling out a full Notepad-style menu set (File / Edit / Format / View / Help) on top of it. It uses Crinkler compression at build time.

TinyRetroPad is basically a wrapper around the RICHEDIT50W control from the WinAPI. DTE versions 1.0+ used the EDIT control with Crinkler cranked and were built up from tiny.asm, then worked down to 890 bytes with Win Defender quite unhappy. Versions 2.0+ backed Crinkler off a bit and use RICHEDIT to gain cheaper access to Courier font and much larger files; 2.0+ was worked down from 995 to 981 bytes as a bare editor. TinyRetroPad then grows from that 981-byte base by adding real menus and dialogs — Open/Save/Save As, Print/Page Setup, Find/Replace/Go To, Font, Word Wrap, Time/Date, and a Ln/Col status bar — landing near 2,476 bytes. Each addition was kept as cheap as possible; the growth log at the top of trpad.asm records what every feature cost in bytes.

If you don't want to bother with downloading the above but need something simple...
I noticed the other day that "edit" was added back to the Windows command prompt which has been missing for a very long time.