SBUF='L'; tam1=SBUF; you can see this code,when i debug it,i was very surprised that tam1=0x00 not 0x4c.I don't know why?You can help me.
I don't know why?
Then you should definitely read chapter 3 of the "bible", aka the 8051 hardware documentation, until you know:
www.nxp.com/.../80C51_FAM_HARDWARE_1.pdf
Because there it says (emphasis mine):
Writing to SBUF loads the transmit register, and reading SBUF accesses a physically separate receive register.