AT89C51ID2-SMSIM ATMEL [ATMEL Corporation], AT89C51ID2-SMSIM Datasheet - Page 28

• Manufacturer Part Number: AT89C51ID2-SMSIM
• Description: 8-bit Flash Microcontroller
• Manufacturer: ATMEL [ATMEL Corporation]

INC is a short (2 bytes) and fast (12 clocks) way to manipulate the DPS bit in the AUXR1
SFR. However, note that the INC instruction does not directly force the DPS bit to a par-
ticular state, but simply toggles it. In simple routines, such as the block move example,
only the fact that DPS is toggled in the proper sequence matters, not its actual value. In
other words, the block move routine works the same whether DPS is ’0’ or ’1’ on entry.
Observe that without the last instruction (INC AUXR1), the routine will exit with DPS in
the opposite state.
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