In assembly, this questions were given like that 1. Real mode allows access to m

Question

In assembly, this questions were given like that

1. Real mode allows access to memory below which memory address?

2. Under real and protected mode, the far jump modifies the current instruction address by changing which register or registers?

3. Under real and protected mode, the near jump modifies the current instruction address by changing which register or registers?

4. Under real mode, briefly explain what happens when the PUSH BX instruction executes. Make sure to show where BH and BL are stored. Assume that initially SP=0100H and SS=0200H. Recall that in the x86 family, the stack grown downwards, toward lower addresses, and the SP is pointing the to top of the stack (most recently pushed value).

Explanation / Answer

In real mode a intel x86 processor can address memory starting from 0x000000 to 0x10FFEF. In real mode the far instruction the CS and IP registered are modified to given segment and offset address respectively.In protected mode the difference is the CS is interpreted as location of descriptor. In near jump the IP register is modified in both cases. When executing PUSH BX instruction first the SP will be decremented to 00FEH then the contents of BX would be written to 02000H+00FEH=020FEH address.The important point is 1st decrement then write.

Related Questions

Navigate

• Browse (All)
• Browse I
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.