> Because it is so tied to the underlying hardware
Firmware has changed over the years, as have the devices we embed it into. Thee devices are much more complex and capable, sometimes, smarter than the computers they connect to. I have worked with devices that ran MS-DOS-like OSs and applications on 386-class processors with built-in printers running a real-time Unix-like OS on a 32-bit RISC processor.
Also, many different devices share common hardware and designs. Hundreds of routers and other various networking devices currently run OpenWRT firmware instead of their original software. Those little boxes are smarter than the first Unix machines I used and at least an order of magnitude smarter than the Burroughs B-500 mainframe that ran land taxes for a whole city on my first internship. All it lacks is a line printer and tape drives.
Firmware has changed over the years, as have the devices we embed it into. Thee devices are much more complex and capable, sometimes, smarter than the computers they connect to. I have worked with devices that ran MS-DOS-like OSs and applications on 386-class processors with built-in printers running a real-time Unix-like OS on a 32-bit RISC processor.
Also, many different devices share common hardware and designs. Hundreds of routers and other various networking devices currently run OpenWRT firmware instead of their original software. Those little boxes are smarter than the first Unix machines I used and at least an order of magnitude smarter than the Burroughs B-500 mainframe that ran land taxes for a whole city on my first internship. All it lacks is a line printer and tape drives.