A single integrated circuit microcontroller 10 including embedded
erasable/programmable non-volatile memory 12 having a read protection.
Microcontroller 10 can operate within a special mode in which external
circuits may access memory 12 by use of input/output pins 18. When
microcontroller 10 activates this special mode, a read protection flag 13
within memory 12 is checked. The read protection flag 13 may be set during
production of the microcontroller 10 after instructional data or firmware
has been installed onto memory 12. If the read protection flag 13 has been
set, the contents of memory 12 are erased or reprogrammed prior to
allowing access to memory 12. In this manner, external circuits cannot
access instructional data or firmware that is stored in memory 12.
