QNX is a realtime, POSIX-certified, microkernel, network-distributed OS for x86-based machines. QNX can work as a single, logical machine instead and merged so a number of QNX machines on a network. QNX can be scaled down to a small, stand-alone, ROM-based embedded system, or scaled up to a full X Window, TCP/IP, NFS, etc. equipped workstation OS, or scaled out to encompass several hundred nodes on a network acting as a single machine. QNX can also support Doom.