Welcome to PDOS (Public Domain Operating System) and PDPCLIB (Public Domain Project C Library)

There are two major components to the PDOS project.

The most commonly used component, thanks to GCCMVS (port of GCC to IBM mainframe) is PDPCLIB which is a public domain C runtime library which you can link your own C programs against to produce executables with no licencing restrictions (even if you use a compiler, commerical or non-commercial, that does have licencing restrictions). PDPCLIB works on DOS, OS/2, Win32, PDOS, MVS (mainframe) and CMS. The library conforms to the ISO/IEC 9899:1990 (aka ANSI X3.159-1989 aka C90 aka C89) standard. It has no extensions so is particularly good at finding out if your code is truly portable.

Secondly there is a 80386-based operating system, which is designed to be a 32-bit version of MSDOS. A 16-bit 8086 version also exists. Note that the 32-bit version is pure 32-bit and supports pure 32-bit applications. The OS does necessarily switch to 16-bit in order to do BIOS calls though, but this is transparent to applications who never see anything 16-bit. The 16-bit version is capable of running some existing 16-bit MSDOS programs, while the 32-bit version necessarily requires recompilation at a minimum.

You can find documentation for PDOS and PDPCLIB in text files in the downloadables here.

There is also some miscellaneous programs with source code there, including OZPD (snippets of PD code), PDPZM (public domain zmodem), PDCOMM (PD communication routines for DOS, OS/2 and Windows), BBS-related stuff (Devil Dialer C, RSEND, Tobruk), RZSZPE - a port of rzsz (zmodem) to DOS and OS/2, and PDCRC - a set of CRC routines.

Most discussion of PDPCLIB takes place here, amongst mainframe enthusiasts. There is no real discussion group for PDOS although it does get mentioned sometimes in the alt.os.development newsgroup. Anyone interested in making (explicitly public domain) enhancements to either component is most welcome.