MCS@-51PROGRAMMER’SGUIDE AND INSTRUCTION SET
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Data Memory:
The 8051can addressup to 64K bytesof Data Memoryexternal to the chip. The “MOW? instmetion is used to
accessthe externaldata memory.(Refer to the MCS-51Instmction Set, in this chapter,for detaileddeaeriptionof
instructions).
The 8051has 128bytesofon-chipRAM (256bytesinthe 8052)plusa numberofSpecialFunctionRegisters(SFRS).
The lower128byteaof3Uh4 can be accessedeitherbydirectaddressing(MOVdata addr) or byindirectaddressing
(MOV@Ri).Figure 3 showsthe 8051and the 8052Data Memoryorganization.
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