Data Memory - Intel MCS 51 User Manual

MCS@-51PROGRAMMER'SGUIDE AND INSTRUCTION SET
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Data Memory:
The 8051can address up to 64K bytes of Data Memoryexternal to the chip. The "MOW? instmetion is used to
access the external data memory.(Refer to the MCS-51Instmction Set, in this chapter, for detailed deaeriptionof
instructions).
The 8051has 128bytesof on-chipRAM (256bytesin the 8052)plus a numberof SpecialFunctionRegisters(SFRS).
The lower 128byteaof 3Uh4 can be accessedeither by direct addressing(MOVdata addr) or by indirect addressing
(MOV @Ri).Figure 3 showsthe 8051and the 8052Data Memoryorganization.
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