hi anil,

assembler in von neuman architecture data and program occupy same memory space there LC is only location counter the assembler has to keep track of. Being harvard architecure here are two spaces and two location counters one for data and one for code and again in the case of 51 we can have external memories too. may be abbrevation can be corrected as DLC (data location counter). PROGRAM COUNTER is a MCU register abbrevated as PC which keeps track which instruction to be executed next.

abhishek