In the late-1980s, Quantum realized that the market was rapidly moving towards the Portable Operating System Interface (POSIX) model and decided to rewrite the kernel to be much more compatible at a low level. The result was QNX 4. During this time Patrick Hayden, while working as an intern, along with Robin Burgener (a full-time employee at the time), developed a new windowing system. This patented concept was developed into the embeddable graphical user interface (GUI) named the QNX Photon microGUI. QNX also provided a version of the X Window System.