Carl Hamacher: Machine Instruction and Programs-Chapter $2$

Question

Register $R_{1}$ and $R_{2}$ of a computer contain the decimal values $1200$ and $4600$ . What is the effective address of the memory operand in each of the following instructions?

$\left ( a \right )$ $Load$ $20\left ( R_{1} \right ),R_{5}$  Ans-//Displacement.  1220

$\left ( b\right )$ $Move$ #$3000,R_{5}$  Ans-?//Immidiate 

$\left ( c \right )$ $Store$ $R_{5},30\left ( R_{1},R_{2} \right )$ Ans-5830//Indexed

$\left ( d \right )$ $Add$ $-\left ( R_{2} \right ),R_{5}$ Ans-4599//Auto Decrement

$\left ( e \right )$ $Subtract$ $\left ( R_{1} \right )+,R_{5}$ Ans-1200//Autoincrement

Comments

 

Load 20(R1),R5  Ans-//Displacement.  1220 

some of the machienes,  20(R1) decodes as R1[20]

 

Move #3000,R5  Ans-?//Immidiate  

 some of the machienes,  3000 instead of #3000 decodes as Immediates.

like that, we can't guarentee what they mean, Due to that reason, in every COA question they will give the description.

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ok, u mean question incomplete

but question was from hamacher

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then, before the excercise question, they mention some where the meanings in the lesson.

But don't worry, now-a-days generally they will describe in the question

see this question https://gateoverflow.in/3581/gate2006-it-40