Oh frabjous day! Das blinken-litz!! Excellent!!! Now I'm _really_ going to want a stack of these... :-) Hmm. Looking at the original RF11 display panel, some of it may be impossible to really emulate; e.g. it displays the contents of the shift register used to assemble words from the bit stream being read from the disk; it's probably not feasible to emulate that... And of course, many of the error bits only make sense with an actual disk (e.g. the various Timing Track errors). How much bandwidth will you have from the board to the display panel anyway? I assume there will be latches on the display panel, and one sends commands down the link to turn given latches on/off? Looking at the original display panel, although it had the extended memory bits, it didn't show the memory address (it does have the disk address). Maybe we could put that where the shift register display used to be? (And speaking of the original display, I couldn't find a picture of one - does someone have one, or, better yet, an actual RF11, so as to copy the look of it as closely as possible?) Oh, yes, please do!!! I counted up (no doubt you did the same :-), and on the longest row (at the top), there are 30 lights, plus 4 empty spaces for the gaps between blocks, so 36 is good. Will you be grouping them in 3's, with slightly larger gaps between each group of 3? That would really maximize the ability to look just like the old RF11 display panel. And warm white LED's, please (of course :-). I'm really going to have to get going on my UNIBUS PDP-11's. I've mostly been working on the QBUS ones, but if I can have blinking lights... :-) I'm already planning on how I can put /, /bin and the pipe device on separate RF platters, so I can watch the lights and see what the machine is up to.. :-) Noel