> Either the OS broke userland, or it didn't; if it didn't, then the same binary should run just as well today as it did then. I think you're oversimplifing th

> Either the OS broke userland, or it didn't; if it didn't, then the same binary should run just as well today as it did then. I think you're oversimplifing things here. There are many reasons why programs did run on the old OS, but no longer work on the new that are not "new OS broke userland". Some of these boil down to inaccurate or short-term assumptions of the developer. Not exactly userland, but this story [1] why old Windows versions crash on fast processors is an especially entertaining read. The sibling comment by jiggawatts provides good examples. [1] http://www.os2museum.com/wp/those-win9x-crashes-on-fast-machines/ http://www.os2museum.com/wp/those-win9x-crashes-on-fast-mach...