4. (a) Explain the meaning of the terms address bus and data bus in respect of a microprocessor system making reference to memory locations, the direction of information flow and the effect of the bus width. Computer memory is usually expressed in either megabytes (Mbytes) or gigabytes (Gbytes). Calculate the address bus size required to directly address (i) 4 Mbytes of memory and (ii) 1 Gbyte of memory. (2 marks) (b) Draw the truth table for tri-state version of an inverter gate and show the circuit symbol that is used to represent such a gate. Explain the importance of this type of circuitry in the operation of microprocessor systems. (2 marks) (c) () Convert the following to their hexadecimal equivalents and illustrate the method by showing the calculations: 101111012, 4837310. (ii) Convert the following to their decimal equivalents again showing the method used: 101011002, 78AB16. (iii) Convert the following decimal numbers to the BCD equivalents:2910, 84710. (3 marks) (d) Describe the operation performed by each line in the assembly language program shown below. What function is performed by this program? (2 marks) START MOV BX, 0140 MOV AH, 30 MOV AL, 37 MARK MOV [BX], AL INC BX DEC AH JNZ MARK INT 20 (e) Rewrite this program using the LOOP instead of the JNZ instruction. (1 mark)