I finally borrowed a digital camera to photograph the damage to my PDP-8/L parity core stack. The damage is more extensive than I remember. There are the two main areas, but in addition, there are single bits that are missing here and there over the entire area. I do not think it is possible to repair this board without rewiring at least the four core mats on this PCB in toto... that's 128x128 cores for the folks keeping score at home. The wire density is approx 32 per inch. Much work. I won't be doing this anytime soon. Here's some photos of that stack I got back in '82 with a partial PDP-8/L http://www.infinet.com/~erd/retrcomputing/pdp8/pix/coreassy.jpg - external view http://www.infinet.com/~erd/retrcomputing/pdp8/pix/coremat1.jpg - one bad mat http://www.infinet.com/~erd/retrcomputing/pdp8/pix/coremat2.jpg - another one Thanks for all the responses to my original questions. I'm somewhat gratified to see that the can of worms that this thread opened has been strangely on topic. I'm especially interested in hearing the results of the #2 nut core, if it's suitable for display purposes. -ethan _________________________________________________________ Do You Yahoo!? Get your free @yahoo.com address at http://mail.yahoo.com