Got invited to ARM's hq in Cambridge 1-2 months after applying. I was interviewed by one of their hardware engineers. He asked me first if I knew VHDL which I didn't at the time so he asked me to write a program C. He then asked me optimise the program (remove redundant statements to make it faster etc .). As some counting was being performed in the program , I was asked to design a digital counter that could perform such a function. Lastly he asked me to draw the internals of an SoC (System on Chip).