Olin, Others have hinted at transmission line effects, which was my first thought when I read your post, but from your responses this seems not to be the case. The only line you don't say much about is the Vpp line, so I'm thinking the problem might be there. I wonder if you have a series resistor in the line driving the Vpp pin? There is an issue with this line and spikes on the 18 series PICs but I don't know if this also applies when in programming mode. Another thing I would have looked at would have been the rise times of the Vdd and Vpp supplies. In 7 you said that you had looked at fall times, so maybe that was what you looked at next. Whatever it was, I'm wondering if (as 20" of cable is not much) it was only just working in the ZIF socket, and the extra cable was the straw that broke the cammels back? Best regards...Mike. ----- Original Message ----- From: "Olin Lathrop" To: Sent: Sunday, February 08, 2004 10:57 PM Subject: [PIC]: PIC programmer puzzle > Here is a purely academic puzzle, as I've already found a solution. -- http://www.piclist.com#nomail Going offline? Don't AutoReply us! email listserv@mitvma.mit.edu with SET PICList DIGEST in the body