Wow! That was _amazing_ speed, to get that uploaded so quickly (even if you had already scanned it in), considering I only posted my request at 14:32 EDT! Thank you very, very much: that allowed me to complete the DQ11 page on the CHWiki: https://gunkies.org/wiki/DQ11_NPR_Synchronous_Line_Interface The MM was unclear on many points (including the backplanes; the MM says, in 2.3.1.2, "double-system unit", making it sound like the option version uses a 9-slot backplane, but it's actually two 4-slot units). You aren't by any chance sitting any DM11-AA manuals, are you? :-) (The weirdest interface I've ever seen; the shift registers are kept in main memory, resulting in many DMA cycles _per character_.) Noel