The MASSBUS Server daemon (MBS) is the PC software which communicates with the Universal Peripheral Emulator FPGA board. The UPE/FPGA then connects to a Digital Equipment Corporation MASSBUS controller and together the two are able to emulate MASSBUS drives. Presently only a limited number of disk devices may be emulated; however it is the intention to eventually support emulation of many different disk and tape drives.

See the UPELIB and MDE2 repositories for the other components involved with this project.