An apparatus within a device, such as an integrated circuit, for
controlling available capabilities of the device. The apparatus includes
an EEPROM storing a configuration control word having at least one bit, a
configuration control mask having at least one bit, and logic to select a
first operating mode of the device when the configuration control word
does not match the configuration control mask and to select a second
operating mode of the device when the configuration control word matches
the configuration control mask. The first operating mode may indicate full
capabilities of the device and the second operating mode may indicate a
set of reduced capabilities of the device. Additional logic in the device
implements a "write once" feature for irrevocably setting the
configuration control word to match the configuration control mask,
thereby permanently selecting the second operating mode (e.g., reduced
capabilities).