[kibwen]

Each new layer of emulation is new code that needs to be written that wasn't required when the original program in question was written. It's a great approach for software preservation, but the fact that it's necessary shows why the approach of "if it ain't broke, don't fix it" doesn't work. The context of computing is changing around us at all times, and hardware has a finite lifespan.

[josephg]

Eh. Emulators are often tiny in comparison to the programs they emulate. Especially when performance isn't so much of a concern - like when you're emulating software written for computers from many decades ago. A good emulator can also emulate a huge range of software. Just look at programs like dosbox and the like. Or Apple's great work with Rosetta and Rosetta2 - which are both complex, but much less complex than all the software they supported. Software like Chrome, Adobe Photoshop and the Microsoft office suite.

Arguably modern operating systems are all sort of virtual machine emulators too. They emulate a virtual computer which has special instructions to open files, allocate memory, talk to the keyboard, make TCP connections, create threads and so on. This computer doesn't actually exist - its just "emulated" by the many services provided by modern operating systems. Thats why any windows program can run on any other windows computer, despite the hardware being totally different.