1. Other
Mainframe operating systems, such as IBM's z/OS, and embedded operating systems such
as VxWorks, eCos, and Palm OS, are usually unrelated to Unix and Windows, except for
Windows
CE, Windows NT Embedded 4.0 and Windows XP Embedded which are descendants of
Windows,
and several *BSDs, and Linux distributions tailored for embedded systems. OpenVMS from
Hewlett-Packard (formerly DEC), is still under active development.
Older operating systems which are still used in niche markets include the Windows-like
OS/2 from IBM; Mac OS, the non-Unix precursor to Apple's Mac OS X; BeOS; RISC OS;
and
AmigaOS.
Research and development of new operating systems continues. GNU HURD is designed to
be backwards compatible with Unix, but with enhanced functionality and a microkernel
architecture. Microsoft Singularity is a research project to develop an operating system with
better
memory protection.