DOS extenders

'''DJ's GNU Programming Platform (DJGPP) is a software development suite for Intel 80386-level and above, IBM PC compatibles which supports DOS operating systems. It is guided by DJ Delorie, who began the project in 1989. It is a port of the GNU Compiler Collection (GCC), and mostly GNU utilities such as Bash, find, tar, ls, GAWK, sed, and ld to DOS Protected Mode Interface (DPMI). Supported languages include C, C++, Objective-C/C++, Ada, Fortran, and Pascal. It was originally called DJGCC''', and was later renamed from DJGCC to DJGPP when C++ support was added, though the "PP" was said to sta

technology for bypassing the limitations of the DOS operating systems family

API for MS-DOS allowing programs to access protected mode on 386 (and later) CPUs

DOS/4G is a 32-bit DOS extender developed by Rational Systems (later Tenberry Software). It allows DOS programs to eliminate the 640 KB conventional memory limit by addressing up to 64 MB of extended memory on Intel 80386 and above machines.

Software interface that allows the simultaneous running of several DOS programs as well as the direct addressing of the expansion memory in protected mode.