Quote "The 80 bytes remaining of Internal RAM, from addresses 30h through 7Fh, may be used by user variables that need to be accessed frequently or at high-speed. This area is also utilized by the microcontroller as a storage area for the operating stack. This fact severely limits the 8051s stack since, as illustrated in the memory map, the area reserved for the stack is only 80 bytes--and usually it is less since this 80 bytes has to be shared between the stack and user variables."

"This area is also utilized by the microcontroller as a storage area for the operating stack."

Question: If I am using 30H through 7FH as general purpose RAM and the stack gets extended does it extend into this general RAM area. Can my stored data get corrupted?

I am using register bank zero for some basic data manipulation (ie: MOV A,@R0) but am not touching the rest of the register banks so can I use 08H through 2FH for general purpose RAM and write to them directly?

Why does the information you provided in the links say that for "high speed" data manipulation 30H through 7FH should be used. What makes RB1 and up slower if reading and writing directly?