[Repost, now that the list is back up... (Thanks, Jay!)] My old Novell 2010 CP/M computer[1] has suffered a failure in the Data Technologies Corp. DTC520 controller. IIRC, this controller can support up to 2 MFM/ST506/ST412 drives and 4 floppies. In my case it's only hooked up to a single Seagate ST-506 (5MB! Woohoo!), and a single Shugart SA450 5-1/4" floppy. Apparently this controller was not too uncommon in the day. In my case, the DTC520 is installed in the disk subsystem that's separate from the main terminal/computer, and they no longer will talk to each other. The problem seems to be related to the section that handles the IO between this controller and the CPU box. I've replaced one chip (74LS33) that was showing some serious corrosion on the pins/legs, thinking that maybe some of that had migrated into the IC die itself, but no change in behavior. It's still indicating a screwy logic level on one of the gates, but it must be coming in on the inputs. I need a schematic to help me trace the signals. I can't locate anything online. Does anyone have anything that could help me out...schematics, technical description, etc.? Many thanks. - Jared [1] Before there was Novell, Inc., the networking software company, there was Novell Data Systems (NDS), c. 1979. They had the big idea of creating a "Data Management Computer" (DMC) around a 68000, which acted as a micro-mini-mainframe for up to 24 intelligent terminals. While this project never really got off the drawing board, around 1980 NDS added (yet) another CPU to their intelligent terminal and stuck CP/M 2.2 on it. They sold a handful of these (I ended up with one) in an effort to generate a little cash flow while the 'real' project of the DMC was still in works. In the end, it was all a little too late and NDS collapsed in the latter half of 1982. It was at this point that Ray Noorda was recruited to revive the company, and in January 1983, Novell, Inc. was (re)born with the focus of networking primarily IBM PCs. The DMC, by the way, ended up becoming a file server (as opposed to Corvus', 3Com's, et al, 'disk (slice) server' technology) and the rest is history. Later, around 1988, Novell, Inc. dropped all hardware products to focus exclusively on their NetWare software.