To get 386BSD 0.0 booting in a VMware virtual machine, go into the VM’s BIOS Setup and to the hard disk configuration page (just like the first screenshot in the article). With the “Type:” field selected, press the [-] (minus) key once to change “Auto” to “User”, then press down-arrow a few times to navigate to the “LBA Mode Control:” parameter. Press the [-] key again to switch LBA Mode Control from “Enabled” to “Disabled”. Press the [F10] key and [Enter] to save and exit.

Your virtual machine should boot into 386BSD. (Almost instantaneously!)

To explain the failure: 386BSD 0.0 is configured to use the hard drive as an ST506, which only supports CHS addressing. In its default configuration, the VM’s BIOS will use LBA mode to load the bootstrap from disk, but after passing control to the 386BSD first-stage bootstrap (wdbootblk), the bootstrap does not (re)program the Drive/Head register, which means that the IDE controller stays in LBA mode and interprets the bootstrap’s CHS disk read requests as if they were LBA-addressed requests, causing the bootstrap to access the wrong region of the disk when it attempts to load the second-stage bootstrap (bootwd). This does not work out well for the unfortunate guest OS! It transfers control to nonsense code, where it hangs.

Switching BIOS to use CHS ensures that the IDE controller is already in CHS mode when the bootstrap takes control, which allows the bootstrap to load the correct sectors from disk and successfully launch the OS.

Thank you for another fascinating exploration of PC OS history!