Hello .. I designed a 8051 compatible chip. But i have no Develop environment. So, I want to port uVision Debugger to my 8051. All instruction of new 8051 are compatible with MCS-51. but new 8051 has two DPTRs and two DPTR control registers(DPT, DPM). DPC(84h) : select DPTR0 or DPTR1 or Auto toggle DPM(85h) : Select DPTRs mode auto increment or auto decrement or No change after MOVX A, @DPTR. This DPTR features are not compatible standard 8051. How can i port the my new 8051 to Keil uVision Debugger ..? Is it possible my new 8051 to Keil uVision Debugger..? I think that User defined peripheral DLL Design can not solve the Two DPTRs problem.. Thanks for your reading..^^