4. (a) Several integer numbers need to be represented, using 12 bits for each. Some of them are negative and therefore a question arises of their exact representation. One option is to commit the most significant bit (MSB) to representing sign (1 negative, 0 -positive), and then use the rest of the bits to encode the absolute value (sign + magnitude representation). Another is to use the 2s complement representation. Find binary encoding of the following numbers: 2022dec, -2020dec, Odec and -5dec, in sign+magnitude and in 2s complement representation. (8 marks) (b) Find the range of integers that can be encoded in each of these two representations. (3 marks) (C) A portable pollution measurement unit needs to store up to 2,000,000 raw measurement values, each represented using a 32 bit value and a 64 bit time-stamp. Find: (i) the minimum size of its memory in MiB (Mebibytes). (2 marks) (ii) the width of the address bus that is required to allow random access to that memory. (3 marks) Assume: memory locations are one byte in size and the number of address bus lines must by a multiple of 8. (d) Raspberry Pi 3 and Arduino Uno are built around two different types of digital central computing units. Identify these types and briefly explain the key similarities and differences between them. (4 marks)