Why is x86 little endian?

Largely, for the same reason you start at the least significant digit (the right end) when you add—because carries propagate toward the more significant digits. Putting the least significant byte first allows the processor to get started on the add after having read only the first byte of an offset. After you’ve done enough assembly … Read more

What is the difference between FIQ and IRQ interrupt system?

ARM calls FIQ the fast interrupt, with the implication that IRQ is normal priority. In any real system, there will be many more sources of interrupts than just two devices and there will therefore be some external hardware interrupt controller which allows masking, prioritization etc. of these multiple sources and which drives the interrupt request … Read more