1. (a) The Fibonacci numbers are the numbers in the following integer sequence,
ID: 3123766 • Letter: 1
Question
1. (a) The Fibonacci numbers are the numbers in the following integer sequence, called the Fibonacci sequence, and are characterised by the fact that every number after the first two is the sum of the two preceding ones: 0, 1, 1, 2, 3, 5, 8, 13, 21, 34, 55, 89, 114, … etc.
By definition, the first two numbers in the Fibonacci sequence are 0 and 1, and each subsequent number is the sum of the previous two. We define Fib(0)=0, Fib(1)=1, Fib(2)=1, Fib(3)=2, Fib(4)=3, etc. The first 22 Fibonacci numbers given below:
Fib(0)
Fib(1)
Fib(2)
Fib(3)
Fib(4)
Fib(5)
Fib(6)
Fib(7)
Fib(8)
Fib(9)
Fib(10)
0
1
1
2
3
5
8
13
21
34
55
Fib(11)
Fib(12)
Fib(13)
Fib(14)
Fib(15)
Fib(16)
Fib(17)
Fib(18)
Fib(19)
Fib(20)
Fib(21)
89
144
233
377
610
987
1597
2584
4181
6765
10946
Write a MARIE program to calculate Fib(n), where the user inputs n. For example, if the user inputs 7, the program outputs the value 13; if the user inputs 15, the program outputs the value 610; if the user inputs 20, the program outputs the value 6765 etc. You need to write and run the program using MARIE simulator. Please include appropriate comments to make your code readable.[10 marks]
(b) For some values of n, your program will not produce correct results. You can check this by gradually increasing the values of n and checking for the correct outputs. What is the maximum value of n for which your program produces a correct result? Why? Please comment on this [5 marks].
2. You are designing an instruction set for your computer. All the instructions are of same size (11 bits long). The size of an address field is 4 bits. You have already designed 5 2-address instructions and 45 1-address instructions. How many 0-address instructions still you can fit? Justify your answer. [7 marks]
3. Write codes to implement the expression: A= (B + C * D – E) on 3-, 2-, 1- and 0-address machines. In accordance with programming language practice, computing the expression should not change the values of its operands. [8 marks]
Rationale
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 investigate the internal operation of the Central Processing Unit (CPU) and describe how it is used to execute instructions;
be able to investigate and describe in detail the essential elements of computer organisation including internal bus, memory, Input/Output ( I/O) organisations and interfacing standards and discuss how these elements function;
Fib(0)
Fib(1)
Fib(2)
Fib(3)
Fib(4)
Fib(5)
Fib(6)
Fib(7)
Fib(8)
Fib(9)
Fib(10)
0
1
1
2
3
5
8
13
21
34
55
Explanation / Answer
Here is the given program:
ORG 0
LOOP1, LOAD N / load the N value into AC
SKIPCOND 000 /skipcond 000 if AC=0
JUMP END /End loop1
LOOP2, LOAD F1 // load the f value into AC
ADD F2 // add f2 to AC
STORE F3 // F3=F1+F2
LOAD F2 /store f2 into f1
STORE F1
LOAD F3 /store f3 into f2
STORE F2
LOAD N //load N into Ac
SUBT ONE //subtract 1 from N
SKIPCOND 000 //if AC =0
JUMP LOOP2 //Call the loop 2
JUMP END // End loop2
/output
LOAD F3 // AC=F
OUTPUT // output the AC value
END, HALT //halt the process
/variables
N, DEC 10 // you can change the value.
F1, DEC 0 //initilaised f1=0;
F2, DEC 1
F3, DEC 0
/constant
ONE, DEC 1
to fine the fibonaic series for n:
the function i have used here:
L1:fib(n){
while(n>0) // loop runs for n times.
{
f=0;
f=f(1)+f(2)
f1=f2, f2=f
fib(n)
}
b)the maximum value of n for which your program produces a correct result
solution: the varibles contains upto 8 integers maximum. if ORG 100-> starts from memory 100.
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