Auto increment addressing mode | UGC NET

UGC NET 2018

Consider the following statements:  
(i) Auto increment addressing mode is useful in  creating self-relocating code.

(ii) If auto increment addressing mode is included  in an instruction set architecture, then an  additional ALU is required for effective  address calculation.  

(iii) In auto increment addressing mode, the  amount of increment depends on the size of  the data item accessed. 

Which of the above statements is/are true?  Choose the correct answer from the code given  below:  
Code:  
(a) (ii) and (iii) only 
(b) (iii) only  
(c) (ii) only 
(d) (i) and (ii) only

Solution:

Addressing modes:

Addressing modes are the ways through which operands are specified.  

The address field in a typical instruction formats are relatively small.


This address field is used to reference the operand in the memory.

Auto increment addressing mode:

Autoincrement mode is similar to register deferred mode in that the address of an operand is stored in a register at runtime. The contents of the register are incremented each time the instruction is performed in autoincrement mode.

Option (iii) is correct, because
In this mode the address where next data block to be stored is generated automatically depending upon the size of single data item required to store.

Autoincrement Mode = after operand addressing , the contents of the register is incremented.

Option (i) is not correct, because
Self – relocating code takes always some address in memory and hence auto – increment addressing mode is not used for self – relocating code.

Option (ii) is not correct, becuase
Additional ALU is not required for effective address calculation if auto addressing mode is included in an instruction set architecture.

To know moe about addressing modes : click here.