How does this apply to any electronic device with a computer inside though?
Can you run your own software on your television, car, smart fridge, etc?
The default expectation seems to be no, you can't.
Can you run your own software on your television, car, smart fridge, etc?
The default expectation seems to be no, you can't.
The chips Apple makes has fuses they blow inside the chip that prevent it booting/running unsigned code. You can't load your own keys or anything unless you have apples private key or get them somehow to sign some software for you.
A lot micros do have fuses that are similar to prevent firmware from being dumped to protect IP, but when you talk to such devices via like JTAG you can often still tell it load code from external memory and such and not from ROM. This of course depends on the chip, but in my experience most the time it's not as insanely locked down as apple does.
--EDIT-- Like if you look here on this wiki article on JTAG: https://en.wikipedia.org/wiki/JTAG#Connectors
You can see two pictures of some netgear products that have JTAG pins that you can connect to that then let you take control of the device with. This how you have to some times load alternative firmware on some Routers and such. If people didn't do this projects like OpenWrt would not exist. Although, for a lot routers you don't have to connect to jtag pins directly.