Methods and apparatus for dual-boot memory selection, update, and recovery in a programmable device

摘要

Methods and associated apparatus for using a dual-boot capable programmable device and for updating programmed information in such a dual-boot capable programmable device. The apparatus of the present invention includes a primary boot memory device (108), a secondary boot memory device (110), and means for selecting between the two memory devices for purposes of "booting" the dual-boot mode device (100, 114..122). In particular, a reset switch (122) of the apparatus of the present invention resets devices in the dual-boot capable programmable device and is coupled to a selection device (114..120). The selection device (114..120) multiplexes signals from the two boot memory devices onto the corresponding bus signals of the dual-boot capable programmable device. When a "long" reset switch activation is sensed (118), the selection device selects a first of the two boot memory devices for coupling to the programmable device. A "short" activation (120) of the reset switch selects the other boot memory device. The present invention also includes methods (200..214, 400..410) for updating the contents of the two boot memory devices so as to avoid an inoperable state encountered due to failure of the update process in a single boot memory device. In particular, both boot memory devices are updated in sequence. The second memory update (206..214) is prevented if the first memory update (200..202) is determined to have failed (204).