Assembly Segments in opcodes

Question

I noticed that in Assembly segments are used in opcodes.

Example:

MOV DWORD PTR SS:[EBP-30],30

I think that \"PTR SS:\" is used to spec

Answer 1

• SS is Stack Segment
• DS is Data Segment
• PTR - pointer. It's an address.

When you do

mov ax, some_variable

you are really substituting this form "mov ax, ds:[pointer_to_variable]"

In case of SS, you are accessing the value not from DS, but from the stack instead :). Think of segment registers as banks. Data comes from DS, Stack data from SS, Code data from CS, Extra segment is ES.