2 a) (8) Describe how negative numbers are represented using 2's complement. (You may use an example to illustrate your explanation.) b) Explain the advantage, in terms of hardware, of using 2's complement arithmetic. (6) c) (12) Analyze the problem that exists with return addresses if one subroutine is called within another subroutine. Explain how this issue is overcome. With reference to an ARM7 processor explain what each of the four flags indicate if set? d) e) Explain the concept of cache memory and why it is necessary. (8) Total 38