It can be hard to find sometimes.
So due to what amounted to a clerical error by Caldera during a corporate sale, the stablest and most powerful x86 OS of all time supporting 32 Bit protected mode was put into open source for a short while.
There it remains for all time.
They tried to retract it when they realised they had open sourced something very incredible. They couldn't. It was forked at that point and has prospered much better than the closed source version that was copyrighted again. It has gradually acquired FAT-32, NTSC, USB and vastly improved hard drive support for very large disk systems.
Some people think this is just another flavor of DOS but it isn't. It is a multitasking, preemptive threaded operating system with IPC mechanisms, named pipes and DLL segment loading of code. It is very much like Desqview except unlike the garbled ownership and legality of Desqview, this can be installed by anybody anywhere they please. It could be included in hardware without a license.
The kernel will fit onto a floppy disk with room to spare for the VOS Web server. So assuming you have some sort of packet driver (many kinds of configurations are available including serial and parallel port drivers if nothing else) you can connect TCP-IP to this and talk to the world the same way as any other OS. The API developer library is a little rough on documentation but I managed to figure it out a couple years back.
Once you have this running, the means by which you browse to the server are sort of irrelevant. Any browser above IE 5.5 should support the full functionality of VOS.
Reliable reports of this OS running on gas pumps for 20+ years and small real-time monitoring of environmental managers are ubiquitous. The robustness of this OS is better established than Linux by a wide margin if you are talking long-term performance.
It is like Desqview except open source and without X-Windows support. I have used both and I think DR. DOS is the more impressive of the two.