Looks pretty good overall. If your board doesn't have the extra switch that requires also decoding A1 in that addressing block, I see no reason to bother doing so; it sounds like some period hardware also did not bother with that, so it shouldn't introduce any compatibility concerns that were not already present 30-odd years ago.
The idea of linking the bonus addressing lines on the modern SRAM chip to otherwise unused and useless bits in the banking control register (or whatever it was called) is not inherently evil. While that minor design change would cause a very slight behavioral difference and in theory might break some carelessly written software, I do not see that as being a genuine problem. The secondary goal here, if you happen to agree with my prior summary at least, IS to add cool features where they won't interfere with the primary goal of expanding the population of vintage PETs that can be used more or less interchangeably with genuine SuperPETs. (The "more or less" qualifier applies solely to the 6702 dongle-chip omission, which is rendered moot and thus ignorable by the recent posting of Waterloo software images edited to not check for it.) I suppose we will only be able to tell for certain that the change is indeed benign by running period software on an 8032 with the new card installed, or perhaps by making a minor modification to someone's local copy of VICE that would reflect the new behaviour… I personally wouldn't vote for that method as my first choice, though. Perhaps it is irrational of me, but I harbour a minor degree of paranoid mistrust of simulation-based testing for "fringe" platforms (i.e., those for which the emulator software has relatively tiny user bases). The hugely popular family of VICE C64 emulators? Thousands, maybe hundreds of thousands of users; very reliable. I'm certain there were never more than a few tens of thousands of original PET users even in aggregate, though, and if I had to guess, probably well under 5 percent of the original user base retain any interest in it today. Logically, it seems very unlikely that the corresponding VICE binary could possibly be as reliably accurate, simply due to it having been use-tested so much less extensively.
