Chapter 13

Question 1

What is bubble sort

Answer 1

It can sort almost anything in computer.

Question 2

What is execution thread

Answer 2

Step by step instructions connected to each other

Question 3

What is rbt command

Answer 3

come back where we start diversion

Question 4

What is int and iret

Answer 4

int = instruction
iret = return from instruction

Question 5

What is temporary division

Answer 5

There are roundabouts on roads as well that take us back from where we started after having traveled on the boundary of the round. This is the concept of a temporary diversion.

Question 6

What are 2 types of instructions diversion

Answer 6

temporary

permanently

Question 7

What instructions are for permanent diversion

Answer 7

jump

Question 8

What instructions are for temporary diversion

Answer 8

call

Question 9

What is RET

Answer 9

It is return. It takes no arguments and transfers control back to the instruction following the CALL that took us in this subroutine

Question 10

What register is used for the top of stack

Answer 10

Stack pointer (SP)

Question 11

How we can get the physical address of stack

Answer 11

SS:SP combination

Question 12

What is the behavior of SP when stack is pushed

Answer 12

decremented by two

Question 13

Can we push or pop single byte in stack

Answer 13

No

Question 14

What is the difference between push and call in stack

Answer 14

Regarding the stack, the operation of PUSH is similar to CALL however with a register other than the instruction pointer.

Question 15

What is the behavior of SP when stack is pop

Answer 15

incremented by two

Question 16

What register is not modified during sub routine

Answer 16

BX

Question 17

Does operand of PUSH is called a source and operand of POP called destination

Answer 17

Yes

Question 18

What is role of SP in direct call

Answer 18

SP decremented by two

Question 19

What is the role of SP in RET

Answer 19

incremented by two

Question 20

What is the maximum number of parameters a sub-routine can receive

Answer 20

seven

Question 21

Can we use stack pointer in effective address

Answer 21

No

Question 22

Stack should be clear by caller or callee

Answer 22

callee

Question 23

What is stack overflow

Answer 23

If the stack is not cleared or is partially cleared the stack will eventually become full, SP will reach 0, and thereafter wraparound producing unexpected results. This is called stack overflow.

Question 24

What is unit of stack operation

Answer 24

word

Question 25

What is local variable

Answer 25

Another important role of the stack is in the creation of local variables that are only needed while the subroutine is in execution and not afterwards. They should not take permanent space like global variables. Local variables should be created when the subroutine is called and discarded afterwards. So that the spaced used by them can be reused for the local variables of another subroutine. They only have meaning inside the subroutine and no meaning outside it.
The most convenient place to store these variables is the stack. The swapflag we have declared as a word occupying space permanently is only needed by the bubble sort subroutine and should be a local variable. The stack pointer will be decremented by an extra two bytes thereby producing a gap in which a word can reside. This gap will be used for our temporary, local, or automatic variable. mov and push command can start the process of such sub routine.