I think you're taking the table too literally: the Diagnostic ROM *is* the Diagnostic ROM test :-). Generically, it's a dirt-simple memory test which also gives the CPU a bit of a exercise (simple bit manipulation and looping) in the process. At least some of the Diagnostic ROM's also do a checksum on themselves (this is actually a requirement for firmware in some European countries) but I don't know if the 11/44's ROM does this. *Generally*, G-series modules referred to by XXDP+ are modules with special diagnostic purposes. These G-modules are often simulators or exercisers, and in many cases were not often found outside of the manufacturing and repair facilities. Other G-series modules are the components of low-level formatters and dedicated hardware test jigs. Many of these modules, according to the hardware indices I have at hand, were custom-wrapped boards produced in extremely small (sometimes only 1 or 2) quantities, yet they still have G-numbers. For at least your RL11 and RL02's: ZRLG?? Controller Test #1 ZRLH?? Controller Test #2 ZRLI?? Drive Test #1 ZRLJ?? Drive Test #2 ZRLK?? Performance Exerciser ZRLL?? Drive Compatiblity Test ZRLM?? Bad Sector File Utility Running the drive tests or performance exerciser with multiple drives at the same time produces an impressive light show as all the unit lights blink in both regular and random patterns! -- 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