i wan to run my program code, in ram, any 1 know how to do that? after generate hex file, how to store in ram?
The 8051 architecture can only execute from CODE space, and CODE space is read-only.
Therefore your RAM would have to be mapped into XDATA space to be able to write to it, and mapped into CODE space to be able to execute...
erm.... if i using mon51, the user program hav to download to ram, using serial port?
IF you are using MON-51, then the first thing you need to do is to study its Documentation:
http://www.keil.com/support/man/docs/mon51/
What does it tell you about this?
If you don't understand the MON51 manual, then you probably need to go back to the so-called "bible" for the 8051 - which is fundamental to understanding any 8051-based system:
Chapter 1 - 80C51 Family Architecture: www.nxp.com/acrobat_d...ARCH_1.pdf
Chapter 2 - 80C51 Family Programmer's Guide and Instruction Set: www.nxp.com/acrobat_d...UIDE_1.pdf
Chapter 3 - 80C51 Family Hardware Description: www.nxp.com/acrobat_d...WARE_1.pdf
Possibly also some basic Tutorials; eg, www.8052.com/.../tutorial