BSD/OS 4.0 for Intel and Sparc, published by Berkeley Software Design Incorporated.

4 ISO9660 CD-ROM images, install may/may not be bootable from CD.  Boot floppy images are in the root of the binary install ISO. 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 fc+j =VEa +L7m for 64 users)