What this means is that XDF disk images formatted as 80-track 23-sector-per-track images will work with XDF code that honors that format; however, I've not yet been able to test with "real" XDF disk images (ie, disk images created with DiskDump using the experimental --xdf flag). "Real" XDF disk images almost certainly need more work (eg, setting all the sector IDs properly), but the groundwork has been laid.
However, performance will suffer until I can implement RTC interrupts;
also, there may be a problem exposed by the BIOS memory test following a soft reset
Some other interesting bugs were fixed along the way:
the Video component incorrectly assumed that masking a negative number with 0x80000000 would yield 0x80000000 (it actually yields -0x80000000, thank you JavaScript);
the ChipSet component provides a new addCMOSMemory() interface that RAM objects can use to bump the CMOS total to match the actual total;
the CPU properly implements INSW and OUTSW instructions now (kind of important for the AT hard disk controller)