A CMOS microprocessor chip includes an on-chip single-poly EPROM that is process-compatible with the CMOS process used to manufacture the microprocessor. The EPROM is used to store manufacturing and contract related data such as serial number, customer, and process related data such as wafer number test results, binning data, etc. This provides important information for quality and reliability control. The EPROM is also used to control selection of optional microprocessor features such as speed governing, pin-out and I/O bus interface configuration. A third use is for trimming of critical circuit elements and for cache redundancy fault control.