Assume the operating system for LC-3 has had new service routines added to it. Consider the following code fragment that requests one of those new service routines LD R2, B LOOP TRAP x31 ADO R2, R2, -1 Also consider the following partial service routine jump table: ADDRESS CONTENTS хоо31 x0709 x0032 х0527 хооз x0913 хоо34 x0957 A. What address is used by the code above to access the service routine jump table? B. What is the starting address of the service routine called by the code above? C. If the symbol table shows LOOP is address x3801, what is the return address from the service routine? D. What is the machine code for the instruction the service routine uses to return to the code above?

Database System Concepts
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Author:Abraham Silberschatz Professor, Henry F. Korth, S. Sudarshan
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Chapter1: Introduction
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Question 3
Assume the operating system for LC-3 has had new service routines added to it. Consider the following code fragment that requests one of those new service routines:
LD
R2, B
х31
R2, R2, #-1
LOOP
TRAP
ADO
Also consider the following partial service routine jump table:
ADDRESS CONTENTS
x0031
x0709
x0032
x0527
x0033
x0913
x0034
х0957
A. What address is used by the code above to access the service routine jump table?
B. What is the starting address of the service routine called by the code above?
C. If the symbol table shows LOOP is address x3801, what is the return address from the service routine?
D. What is the machine code for the instruction the service routine uses to return to the code above?
Enter the addresses and the machine code as 4-digit hex values in LC-3 format like the following: X01F3
Transcribed Image Text:Question 3 Assume the operating system for LC-3 has had new service routines added to it. Consider the following code fragment that requests one of those new service routines: LD R2, B х31 R2, R2, #-1 LOOP TRAP ADO Also consider the following partial service routine jump table: ADDRESS CONTENTS x0031 x0709 x0032 x0527 x0033 x0913 x0034 х0957 A. What address is used by the code above to access the service routine jump table? B. What is the starting address of the service routine called by the code above? C. If the symbol table shows LOOP is address x3801, what is the return address from the service routine? D. What is the machine code for the instruction the service routine uses to return to the code above? Enter the addresses and the machine code as 4-digit hex values in LC-3 format like the following: X01F3
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Hello, what if the code is 

                   LD R2, B

LOOP        TRAP x32

                  ADD R2, R2, #-1

What should be the answers? And can you explain? 

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