Question 1

Consider the C struct defined below:

    struct data   {
        int marks [100];
        char grade;
        int cnumber;
    struct data student;

The base address of student is available in register R1. The field student.grade can be accessed efficiently using

Post-increment addressing mode, (R1)+
Pre-decrement addressing mode, -(R1)
Register direct addressing mode, R1
Index addressing mode, X(R1), where X is an offset represented in 2’s complement 16-bit representation
       Computer-Organization       Addressing-Modes       Gate 2017 set-01
Question 1 Explanation: 
sruct data
int marks[100];
char grade;
int cnumber;
}; struct data student
Base Address of student is available in R1.
So student.grade can be accessed efficiently by Relative Indexed Addressing Mode.
It is clearly mentioned X is the offset address to be summed with Base Address of R1.

Hence Index Addressing mode X(R1), where X is an offset represented in 2’s complement 16-bit representation.
⇾ Relative, Base Indexed & all subtypes of Indirect addressing modes are used with Arrays.
Question 2
Which of the following is/are true of the auto-increment addressing mode? I.It is useful in creating self-relocating code II.If it is included in an Instruction Set Architecture, then an additional ALU is required for effective address calculation III.The amount of increment depends on the size of the data item accessed    
I only
II only
III Only
II and III only
       Computer-Organization       Addressing-Modes       Gate-2008
Question 2 Explanation: 
I : Self relocating code always takes some address in memory. So auto-increment mode is not used for self relocating code. Hence this statement is wrong.
II. An additional ALU is not necessary for auto-increment. So this statement is wrong.
III. In auto-increment addressing mode the address where next data block to be stored is generated automatically depending upon the size of single data item required to store. This is based on pointer arithmetic. So this statement is true.
Hence option C is the answer.
Question 3
Which of the following statements about relative addressing mode is FALSE?
It enables reduced instruction size
It allows indexing of array elements with same instruction
It enables easy relocation of data
It enables faster address calculations than absolute addressing
       Computer-Organization       Addressing-Modes       Gate 2006-IT
Question 3 Explanation: 
As relative address are calculated from the absolute address. So relative addressing cannot be faster than absolute addressing.
Question 4
(i) and (iv)
(i) and (ii)
(ii) and (iii)
(i), (ii) and (iv)
       Computer-Organization       Addressing-Modes       Gate-2004
Question 4 Explanation: 
Absolute Addressing:
A fixed address in memory which indicates a location by specifying a distance from another location. In this displacement type addressing is preferred.
So, option A is false.
Based Addressing:
This scheme is used by computers to control access to memory. In this pointers are replaced by protected objects which can be executed by kernal (or) some other privileged process authors.
So, this is suitable for program relocation at runtime.
Relative Addressing:
The offset of the relative addressing is to allow reference to code both before and after the instruction.
This is also suitable.
Indirect Addressing:
Which leads to extra memory location which can be not suitable at run time.
This is not suitable.
→ Only Based Addressing and Relative Addressing are suitable.
Question 5
In the absolute addressing mode
the operand is inside the instruction
the address of the operand is inside the instruction
the register containing the address of the operand is specified inside the instruction
the location of the operand is implicit
       Computer-Organization       Addressing-Modes       Gate-2002
Question 5 Explanation: 
The operand is inside the instruction---Immediate addressing.
The operand is inside the instruction --- absolute addressing.
The register containing the address of the operand is specified inside the instruction --- Register addressing.
The location of the operand is implicit --- Implicit addressing.
Question 6
A certain processor supports only the immediate and the direct addressing modes. Which of the following programming language features cannot be implemented on this processor?
Recursive procedures with local variable
All the above
       Computer-Organization       Addressing-Modes       Gate-1999
Question 6 Explanation: 
A) Cannot be implemented because pointers need indirect addressing mode.
B) Cannot be implemented because arrays need Register indexing.
C) Records also needs pointers which needs indirect addressing modes, so this also cannot be implemented.
D) Recursive procedures needs stack, and so it needs stack pointers which inturn needs indirect addressing. So this also cannot be implemented.
Question 7
Which of the following addressing modes permits relocation without any change whatsoever in the code?
Indirect addressing
Indexed addressing
Base register addressing
PC relative addressing
       Computer-Organization       Addressing-Modes       Gate-1998
Question 7 Explanation: 
In PC relative addressing there is no change in the code.
Question 8
Relative mode of addressing is most relevant to writing
position – independent code
shareable code
interrupt handlers
       Computer-Organization       Addressing-Modes       Gate-1996
Question 8 Explanation: 
The main advantage of PC- relative addressing is that code may be position independent, i.e., it can be loaded anywhere in memory without the need to adjust any address.
Question 9
The most relevant addressing mode to write position-independent codes is:
Direct mode
Indirect mode
Relative mode
Indexed mode
       Computer-Organization       Addressing-Modes       GATE-1987
Question 9 Explanation: 
Relative mode since we can just change the content of base register, if we wish to relocate.
There are 9 questions to complete.
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