Hello

In most cases, when programming in assembler of course, I do clear A before using that instruction, only using DPTR with the correct address.

However, sometimes, when not a complete string is to be read, but to look up a single byte only in a lookup table in a buffer of up to 256 bytes, I prefer to load DPTR with the buffer start address and use A as an index to the buffer. This avoids to calculate the address before and put that address to DPTR and then clear A; because the 8051 caculates the address for me.

Note that this can be done without using DPTR at all, I use MOVC A,@A+PC sometimes like this:
; A is the table index 0 to 252
ADD A, #3 ; compensate for LJMP after MOVC
MOVC A,@A+PC
LJMP BehindTable
Table:
...
BehindTable:

Best reagrds