Somehow reading the chapter on "CPU registers of the 8051 variants"user guide 02.2001 about Macro Assembler and Utilities on registers R0-R7 give me the impression that the 8051 has a on-chip R0-R7 that in the chip but not in DATA area 0x00 - 0x1F. However, using register bank 0 and much debugging, realised it is not. The R0-R7 resides on the DATA area 0x00-0x1F. Is it just me or the documentary on that is confusing?
yes, these 8051 bibles make it very clear. thanks!