copying error with memcpy when interrupt timer 1 is enable ! keil c51 v7.00 this is the start of timer 1 interrupt: DPH, DPL, DPH1, DPL1 , WMCON are correctly saved.... ; FUNCTION T1_int (BEGIN) 0000 C0E0 PUSH ACC 0002 C0F0 PUSH B 0004 C083 PUSH DPH 0006 C082 PUSH DPL 0008 C085 PUSH DPH1 000A C084 PUSH DPL1 000C C096 PUSH WMCON 000E 5396FB ANL WMCON,#0FBH 0011 C0D0 PUSH PSW 0013 75D000 MOV PSW,#00H 0016 C000 PUSH AR0 0018 C001 PUSH AR1 001A C002 PUSH AR2 001C C003 PUSH AR3 ..... and POP at the end ..... Why in lib function COPYA2 the active DPTR is never initialised, only inverted ? XRL WMCON,#04 when I don't use the second DPTR (NOMODA2) the copy is OK even when interrupted