The Von Neumann model for a computer system uses registers.

1. (a)(i)Describe the role of the following special purpose registers in the fetch-execute (F-E) cycle. Memory Address Register (MAR) Memory Data Register (MDR)[4]
2. (a)(ii)Another special purpose register is the Index Register. Identify one other special purpose register used in the Von Neumann model for a computer system.[1]
3. (b)(i)In the following table, each row shows the current contents of the ACC in binary and the instruction that will be performed on those contents. Complete the table by writing the new contents of the ACC after the execution of each instruction. Current contents of the ACC Instruction New contents of the ACC 01010101 XOR 101 11110000 AND 104 00001111 LSL #4 11111111 OR 102[4]
4. (b)(ii)The following table contains five assembly language instruction groups. Write an appropriate assembly language instruction for each instruction group, using the given instruction set. The first one has been completed for you. Instruction Group Instruction Data movement LDM #2 Input and output of data Arithmetic operations Unconditional and conditional instructions Compare instructions[4]
5. (b)(iii)The opcode LDM uses immediate addressing. The opcode LDD uses direct addressing. Identify and describe one additional mode of addressing. Mode of addressing Description[2]