Abstract: A method for varying the type of function selected on a chip (for example, after completion of manufacturing) may include the steps of providing predetermined fuse arrangements which individually or in combination correspond to each type of function on the chip and providing disable control lines having fuses to each of the predetermined fuse arrangements. When one of the types of circuits is selected, the predetermined fuse arrangement individually or in combination corresponding to that selected type of function is blown. The blowing of fuses may change the functionality of the chip directly or may perform a complex procedure such as controlling a portion of a decoding scheme which may radically change the function of the chip. To prevent further blowing of predetermined fuse arrangements, the fuses in disable control lines to each of the predetermined fuse arrangements may be blown, eliminating further selection of types of function.

Abstract: The present invention provides a clocking circuit allowing individual macrocells in a particular macrocell block of a CPLD to use different polarities of the same clock. The input clock pin can now drive all the macrocells directly, which can eliminate additional buffering states and improve the clock to out timing, Tco, by (for example) 300 ps. The clocks are presented directly to the clock selection multiplexers for each macrocell. Additional functioning may be realized by implementing additional configuration bits inside the clocking architecture.

Abstract: The presently preferred embodiment of the invention provides a memory structure that eliminates the thick gate associated with the offset of the FAMOS transistor and reduces the standard 225 angstrom offset to a 100 angstrom offset required for FN tunnelling. The 100 angstrom offset is realized uniformly underneath the entire area of the floating poly. The invention uses transistors each having a 100 angstrom offset to realize both erase and programming functions. The present invention realizes an erasing feature through an erase transistor and an ERL line. However, the programming of the cell will be realized through the programming transistor. As a result, a double poly flash cell will function like an EEPROM. This functioning eliminates the hot electron tunnelling required to program conventional double poly flash cells and results in a significant reduction in chip real estate. The reduction allows the present invention to be scaled to next generation architectures.