Abstract: A single chip microcomputer with patching and configuration is provided with blocks of patch memory which may be patched over faulty and/or obsolete areas of the microcomputer's memory map under control of starting address registers which are implemented in on-board non-volatile memory. The starting address registers, and enable registers which control whether each patch block is placed in the memory map, are programmable under control of the microcomputer's CPU. Newly programmed values in these registers are not effective to alter the memory map until a reset sequence enables a latch. In particular embodiments, patch blocks may overlie mask ROM, internal EPROM and/or EEPROM, external memory or devices or any other desireable portion of the memory map.