System V-derived, big endian MIPS UNIX with BSD and POSIX extensions, for the computer systems made by the former MIPS Computersystems, Inc. including the MIPS Magnum 3000 (also known as mipsco), Microsoft/MIPS Magnum 4000 (Jazz), M120 and more.
RISC/os also had maybe the most inflated syscall interface as can be seen in this header file defining the RISC/os syscalls. The basic structure is:
* 0 - 999 System V Release 4 flavored syscalls * 1000 - 1999 System V syscalls. All flavors of IRIX use this number range as well. * 2000 - 2999 BSD 4.3 syscalls * 3000 - 3999 POSIX syscalls
The Linux system call interface is derived and extends this by adding (see arch/mips/include/asm/unistd.h):
* 4000 - 4999 Linux O32 syscalls * 5000 - 5999 Linux N64 syscalls * 6000 - 6999 Linux N32 syscalls