Hi,

the page mode on the 8051 was invented to write more compact code.
On using external memory or memory mapped peripherals you can access it with the 16 bit register DPTR.

But in several cases you need a second pointer or must only access data inside a small 256 byte area. In all such cases you can use port P2 to select the appropriate 256 byte page and after it you can use up to 8 pointers (R0, R1 on all four register banks) to access it.
The result was less code space consumption and faster execution time.


Peter