Question: Discuss the pros and cons of architectures with a 64-bit word size versus those with a 32-bit word size. Which applications are likely to benefit most? [4 marks] (c) If you were a processor architect targeting embedded applications where memory is a scarce resource, how might you design a RISC-like instruction set that will achieve efficient use of memory? [6 marks] 2 Digital Communication II (a) Explain the r?ole of the checksum mechanisms in OSI layers 2, 3 and 4 of the Internet Protocols. [9 marks] (b) An ARM assembly code implementation of the IP/TCP checksum function appears below. Annotate this with comments that explain the code. sub r3, r3, #16 loop: ldmia r2!, {r6-r9} adds r4, r4, r6 adcs r4, r4, r7 adcs r4, r4, r8 adcs r4, r4, r9 adcs r4, r4, #0 adc r4, r4, #0 subs r3, r3, #16 bxx loop add r3, r3, #16 [6 marks] (c) traceroute is a commonly used diagnostic tool in the Internet. Explain how it works, making reference to its use of the TTL Expiry facility of ICMP, and the circumstances under which it might generate misleading or incorrect output.