A few details for the curious: It's housed in a BA-11 box with 3 controller cards. The Massbus paddles fit into that box and terminate in flat ribbon cable, not the massive cables. The DRAM chips are 4116s. manx tells me that these documents were known to exist: PartTitleStatus EK-0ML11-TD *ML11 Technical Description <https://www.vt100.net/manx/part/dec/ek-0ml11-td/>* EK-0ML11-TM *ML11 Technical Manual <https://www.vt100.net/manx/part/dec/ek-0ml11-tm/>* EK-0ML11-UG *ML11 User's Guide <https://www.vt100.net/manx/part/dec/ek-0ml11-ug/>* But they are not online. So I can't say whether they are 18 bit compatible.