Just a word of warning concerning a PLA sub selling on eBay that also uses the XC9536XL: Me and Fredric have examined this product and we were curious as to why it would carry the 5ns version of that chip - PLAnkton carries the 10ns version.
Considering the speed of a C64 and that most other PLA substitutes have problems because they are actually too fast, there is absolutely no logical reason to use a faster chip that also turns out to be considerably more expensive - PLAnkton uses the 10ns version of the XC9536XL, it is the slowest and cheapest member of that family of chips and only it has the necessary characteristics to faithfully replicate the slow N82S100 on which the Commodore PLA was based.
Upon closer inspection, we have determined that the reason why the 5ns version was chosen is because it is in fact Chinese made counterfeits. Chinese clones of the XC9536XL are all marked as 5ns but they have all sorts of different response speeds. Also, on these counterfeit ICs the slew rate limiter as well as the low power mode don't operate properly. Of course, they are considerably cheaper than all genuine Xilinx XC9536XL, no matter what their rated speed may be.
PLAnkton uses only genuine Xilinx XC9536XL circuits purchased from Digikey, an authorized distributor of Xilinx products. We program these chips to provide the most accurate reproduction of the behavior of a genuine C64 PLA as well as the lowest possible power consumption and only a genuine Xilinx circuit can achieve this level of accuracy.
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