The last version of BSD/OS published by the BSDi business unit of Walnut Creek before it divested it's BSDi assets to Wind River Systems. 4 ISO9660 CD-ROM images, install is bootable from CD. The system uses old-style UFS so it won't cleanly work with drive sizes over 4GB or so. (when the installer asks for a serial, enter K8ix @Vix @Dnw for unlimited users)