Windows 1.01 was the first publicly released retail version of Windows. Windows 1.01 was released on 1985-11-20 and discontinued on 2001-12-31. According to Microsoft, Windows 1.01 is an "Operating Environment" designed to run on top of MS-DOS, rather than a standalone operating system. Additional applications were bundled with Windows, including Write (a word processor), Paint (a graphics drawing program), Reversi (a game), and various utilities (Clock, Calendar, Calculator).
Windows 1.01 initially retailed for $99 in the US or the equivalent of $224.32 in 2017 (accounting for inflation). Windows 1.01 is designed to run on MS-DOS 2.00 to 5.00. If it is loaded on any version of MS-DOS higher than 5.00 (without using setver on win100.bin), it will crash on startup.
A DEC VAXmate OEM build for this version was leaked in 2016-08-08 on a blog and resurfaced in 2017-04-30 on BetaArchive. This OEM version is identical to this version, but replaces the boot screen logo from Microsoft to Digital and changed the version identified on the setup and boot screen to "1.01.11". Alongside, it will also install a minimal install on a floppy by default.