at89c51re2-slsem ATMEL Corporation, at89c51re2-slsem Datasheet - Page 20

• Manufacturer Part Number: at89c51re2-slsem
• Description: At89c51re2 8-bit Flash Microcontroller
• Manufacturer: ATMEL Corporation

20
AT89C51RE2
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.
0010 70F6JNZ LOOP ; check for 0 terminator
0012 05A2 INC AUXR1 ; (optional) restore DPS
7663B–8051–03/07