Difference between `bx` and `bp`?

assembly masm masm32
tina nyaa picture tina nyaa · Sep 2, 2011 · Viewed 12.1k times · Source

What is the difference between bx and bp in assembly? Example here:

mov bx, 1h
mov bp, 1h

Do they reference to the same memory? Is it the same with ss and sp?

Answer

cnicutar picture cnicutar · Sep 2, 2011

In x86 the registers bx and bp are totally unrelated. The only common thing about them is the word base.

  • bx (base index) is a general-purpose register (like ax, cx and dx), typically used as a pointer to data (used for arrays and such)
  • bp (base pointer) is typically used to point at some place in the stack (for instance holding the address of the current stack frames)

Again, ss and sp are different as well.

  • ss (stack segment) is a segment register (like cs, ds and es). It holds the segment used by the stack.
  • sp (stack pointer) points at the top of the stack

Related questions

Outputting Hello World in MASM using WIN32 Functions

Contents Intro Code Assembling and Running Miscellaneous Question 1. Intro This isn't a question per se (though there is one at the bottom) but a HelloWorld app for people on StackOverflow to experiment with. When I was first trying programing in …

Read More
mov ax, bx vs. mov ax, [bx]

What is the difference between the following two lines? mov ax, bx mov ax, [bx] If bx contains the value 100h and the value at memory address 100h is 23, does the second one copy 23 to ax? Also, what is the …

Read More
Division in 8086 Assembly in MASM

I am writing this assembly program in 8086, but it is not working properly. The quotient and remainder prints out as some random symbols even though I use single digit numbers. Can someone please point out the errors/mistakes in the …

Read More