MOV A,33h; Means: move a number from address 33 hex. to accumulator
MOV A,@R0; Means: Store the value from the register whose address is in the R0 register into accumulatorOn indirect addressing, registers R0, R1 or Stack Pointer are used for specifying 8-bit addresses. Since only 8 bits are avilable, it is possible to access only registers of internal RAM this way (128 locations when speaking of previous models or 256 locations when speaking of latest models of microcontrollers). If an extra memory chip is added then the 16-bit DPTR Register (consisting of the registers DPTRL and DPTRH) is used for specifying address. In this way it is possible to access any location in the range of 64K.