History: The NEC-8801 was the precursor to the hugely popular and market dominating proprietary Japanese NEC PC-9801 computer. Popular in its own right, the 8801 helped bring the Japanese PC market to a near monopoly under NEC during the 1980s, setting the 9801 up for later success.
The Files: After wrestling with improperly named and missing BIOS files from other sources, I finally found a set that works - so here it is.
Unpack the BIOS files straight into the directory of the 8801 emulator of your choice.
I've tested 3 NEC8801 emulators and they all work with these.
Run Emulator (for example) X88000.EXE
Respond "0" to the "How many Files" question
Go to the disk menu option.
Choose a game file - usually you'll want disks 1 & 2 in at the same time.
If the game does not autostart, type "RUN" and press enter, even if the screen shows black-on-black.
Note that 8801 games use the function keys, and F10 may toggle your windows file menu instead of what it should do in an 8801 game. Some 8801 emulators deal with this better than others. Some use English menus, others Japanese, some deal with sound better than others, its all about what works best for you. A web search will easily pull up some choices for "NEC 8801 Emulator".
If you don't care about the sound or just want to try a game out, I found X88000 worked best with Master of Monsters (for instance), due to it not activating the windows File menu in the window toolbar. F10 starts the game in MOM.