https://en.wikipedia.org/wiki/IBM_Common_User_Access https://en.wikipedia.org/wiki/IBM_Common_User_Access It doesn't pre-date the C/V/X/Z shortcuts, it's just

https://en.wikipedia.org/wiki/IBM_Common_User_Access https://en.wikipedia.org/wiki/IBM_Common_User_Access It doesn't pre-date the C/V/X/Z shortcuts, it's just that those conflicted with things like CTRL-C to interrupt. I don't think hardware interrupts are involved here. It's not a particularly early DOS convention either, Wordstar-style shortcuts were popular before it.