From Apple'svarious files on 8.1, here are two more tidbits worth highlighting:
AppleTalk work-around explained Apple's Mac OS 8.1 Late Breaking Tips TIL discusses how to turn off AppleTalk for those cases where, even after apparently turning it off, you still get a "serial port in use" message (a problem previously covered here on MacFixIt). Alternatively, you can also set up Location Manager (or certain other third-party Control Strip modules, such as FruitSpeak) to switch settings.
HFS and 680x0 Macs As noted in the About Mac OS Extended Format file: "680x0 processor computers can not use a hard disk initialized with Mac OS Extended format as the start up disk, but the Mac OS Extended format can be used on additional disks connected to a 680x0 computer running Mac OS 8.1 or later. In addition, you can not select a hard disk initialized with Mac OS Extended format in the Virtual Memory section of the Memory control panel."