Hi Vinod,

Have you read the Ultra High Speed Flash Microcontroller User's Guide? See it at http://pdfserv.maxim-ic.com/arpdf/Des...rguide.pdf It details the instruction set timing and answers your questions.

The '420 is a single clock per machine cycle uC. You might have been reading something describing the original 8051. Note that you will have to look up each instruction, as not all instructions execute in a single machine cycle.

Dennis