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Assignment 2: MARIE & ISA
Explain each step by step
1. A digital computer has a memory unit with 16 bits per word. The instruction set consists of 122 different operations. All instructions have an operation code part (opcode) and an address part (allowing for only one address). Each instruction is stored in one word of memory. [4 marks]

a) How many bits are needed for the opcode?
b) How many bits are left for the address part of the instruction?
c) What is the maximum allowable size for memory?
d) What is the largest unsigned binary number that can be accommodated in one word of memory?

2. Consider the MARIE program below. [5 marks]

a) List the hexadecimal code for each instruction. [1.5 marks]
b) Draw the symbol table. [1.5 marks]
c) What is the value stored in the AC when the program terminates? [2 marks]
Addr Label Instruction
100 Start, Load A
101 Add B
102 Store Temp
103 Load C
104 Add D
105 Add Temp
106 Store F
107 Output
108 HALT
109 A, DEC 5
10A B, DEC 3
10B C, DEC 4
10C D, DEC 13
10D E, DEC 3
10E Temp, HEX 00FD
10F F, HEX 00FE
3. Write code to implement the expression
F = (A+B) /(C*D*E) on 2-, 1- and 0-address machines. [6 marks]

Online submission is required for this assignment to check plagiarism.

This assessment task covers topics on CPU operation and Instruction Set Architecture, and has been designed to ensure that you are engaging with the subject content on a regular basis. More specifically it seeks to assess your ability to:
• be able to define and appropriately use computer systems terminologies;
• be able to describe the essential elements of computer organisation and discuss how the elements function;
• be able to describe the basic instruction set architecture of a simple computer;
• be able to discuss the general trends in computing technologies including examples of leading edge developments.
Marking criteria
The following marking criteria will be used to mark this assignment:

Questions Fail ( 50%) Pass (50% - 64%) Credit (65% - 74%) Distinction (75% - 84%) High Distinction ( 84%)
Question 1 &2 Incorrect answer with no demonstration of understanding the topic. Student demonstrate the understanding, however the calculations are incorrect. Answers are correct, omission of few calculations. Answers are correct and clearly show the calculations
Question 3 Answers are incorrect Total marks available = 5 marks ·
Subtract the marks are set in marking criteria for each incorrect or missing instruction value in the code assembly;
Subtract 1 mark for each incorrect or missing symbol;