Is there any reasion that setting CCAP4H to zero should cause the DPTR to incrament? My assembly code sets the PWM mode "MOV CMOD,#0 MOV CCAPM4,#42H MOV CCAP4H,#0h,SETB CR " and this is fine. I can set he value of CCAPM4 to anything after initialization but zero. If I set CCAPM4 to zero the DTPR gets incramented by one. There are only two ISR being used (int1 for the RTC and the SINT)and the DPTR is pushed for each. I included a trap for a false interrupt for PCA but does not get there. I have simulated the code using Keil uVision2 and of course it works fine.

My quick solution is don't use the strategy instruction following a command to to zero the CCAPM4, then all is well.

Is there anytnig I'm missing in the hardware archicture that would cause this?

Thanks,

Joe