Most CPUs have assembly instructions called something like "shift left/right" or "rotate left/right". That implies an endianness, and it is (to my knowledge) always the endianness of normal written numbers - most significant is "left". That is, big endian.
Bit-endianness is only relevant for serial transmission. You only have to worry about it in circumstances where you have hardware that assumes a different bit order than what you're communicating with. Otherwise, the internal layout of words is abstracted and you can ignore it.
It's relevant when dealing with the control registers of peripherals, even if that's over a parallel bus. It's at least important that you have the same bit order as the peripheral.
They do ultimately have an order if transmitted over a network!
They do if transmitted over a serial port. But today's networks encode whole bytes or more into the symbols actually sent over the wire/air, so there's not really any way to point out on an oscilloscope trace where particular bits out of a byte are sent in a specific order.
Comments
The bits in a byte do not have a defined endianness!
Most CPUs have assembly instructions called something like "shift left/right" or "rotate left/right". That implies an endianness, and it is (to my knowledge) always the endianness of normal written numbers - most significant is "left". That is, big endian.
Bit-endianness is only relevant for serial transmission. You only have to worry about it in circumstances where you have hardware that assumes a different bit order than what you're communicating with. Otherwise, the internal layout of words is abstracted and you can ignore it.
It's relevant when dealing with the control registers of peripherals, even if that's over a parallel bus. It's at least important that you have the same bit order as the peripheral.
I seem to recall discussion of this in the RFC. They do ultimately have an order if transmitted over a network!
But most of us are used to getting them a byte at a time through the memory interface so we are ignorant of this.
They do if transmitted over a serial port. But today's networks encode whole bytes or more into the symbols actually sent over the wire/air, so there's not really any way to point out on an oscilloscope trace where particular bits out of a byte are sent in a specific order.
Wow! I didn’t know that