Ron Copley's venerable "Field Guide to Q-bus and Unibus Modules" contains, in most cases, the option name as well as the module number in the description. For example: M8053-AA DMV11 Q Microprogrammed controller (needs one of M5930- M5931) (Also M8053-AB, -AC, -ETC) Generally, a "D" at the front means it's some sort of communications option, a "M" means memory, a "K" means CPU, "R" means disk controller, a "T" means a tape controller, an "A" means an A/D or D/A converter, a "V" means some sort of video-related hardware, and "L" means either a line printer or a linear module. I'm sure someone will come up with many options that don't quite fit into this scheme :-). The field guide claims at its top: *This list may always be found on sunsite.unc.edu, in the following *directory: */pub/academic/computer-science/history/pdp-11/hardware/field-guide.txt *(Tonnes of stuff here... thanks, Tim!) -- Tim Shoppa Email: shoppa(a)trailing-edge.com Trailing Edge Technology WWW: http://www.trailing-edge.com/ 7328 Bradley Blvd Voice: 301-767-5917 Bethesda, MD, USA 20817 Fax: 301-767-5927