In the PC world this has been done couple of times, eg https://en.m.wikipedia.org/wiki/I2O https://en.m.wikipedia.org/wiki/I2O from the late 90’s. I think the

In the PC world this has been done couple of times, eg https://en.m.wikipedia.org/wiki/I2O https://en.m.wikipedia.org/wiki/I2O from the late 90’s. I think the real reason why it works for mainframes is that their operating system is so primitive, so it’s easy to cross layers - because there are so few of them. z/OS is closer to MS-DOS than to Unix in that regard.