The 5170 AT hard disk controller is limping along now, so I'm getting ready for a 1.15.4 release

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)

my_modules/pcjs-client/lib/ram.js

@@ -180,6 +180,7 @@ RAM.prototype.reset = function() {
             if (MAXDEBUG) this.status("ROM BIOS memory test has been disabled");
             this.bus.setWordDirect(ROM.BIOS.RESET_FLAG, ROM.BIOS.RESET_FLAG_WARMBOOT);
         }
+        if (this.chipset) this.chipset.addCMOSMemory(this.addrRAM, this.sizeRAM);
     } else {
         this.error("No RAM allocated");
     }