So many discontinued Microsoft products not listed: Xenix, Microsoft OS/2, Multiplan, Microsoft COBOL, Microsoft Fortran/PowerStation, Microsoft Pascal/QuickPascal, the classic Microsoft Basic line (BASIC/BASICA/GW-BASIC/QuickBASIC/QBASIC/PDS/VBDOS), MS-DOS, MSX-DOS, Microsoft Adventure, Microsoft Decathlon, Z-80 SoftCard, Microsoft Delta (the version control system), Windows NT OS/2 subsystem, Presentation Manager for Windows NT (an add-on which allowed you to run OS/2 1.x GUI programs on Windows NT), FoxPro, Visual FoxPro, Visual Test, Microsoft File (the classic MacOS database app), Microsoft Mail/Schedule+, Microsoft LAN Manager, Microsoft Services for Netware, Visual J++, Visual J#, Microsoft Money, Microsoft LISP (actually reselling muLISP, which Microsoft earlier had sold under its own name), InfoPath, Entourage, FrontPage, Vizact, Object Packager

One ambiguity in all this is what counts as a "product". There have been a lot of things which have disappeared over the years – such as apps bundled with Windows 3.x which have disappeared in newer versions (for example, Reversi or Cardfile) – but which were never sold as independent products, do they count? And what about stuff which is discontinued but has an upwardly compatible replacement – Visual C++ is the successor to the Microsoft C/C++ line going back to the 1980s, in a somewhat similar way VB.NET is successor to the Microsoft BASIC line going back to the 1970s. Microsoft Mail was replaced by Exchange/Outlook, etc. Xenix, OS/2 and LAN Manager were effectively replaced by Windows NT, the POSIX/Interix/SFU/SUA subsystem was effectively replaced by WSL. There are also products Microsoft sold on behalf of third companies, whether rebranded or under their original names (I mentioned muLISP; muMATH and R:Base are other examples)