I just talked to a guy that worked (in an executive type position) years ago at a company called MeasureX. According to him, MeasureX bought a lot of HP2100's for their process control stuff. They got tired of the problems associated with the cpu card set consisting of 8 cards (9 with DMA - er - DCPC in HP lingo) and the problems with the wire-wrapped backplanes. They redesigned the 2100 cpu to fit on a single card - one PCB - no wirewrapping, all etched traces. They sold this redesigned cpu (actually just a relayout of the circuits) back to HP, and HP dubbed it the 21MX (where the MX is for MeasureX). This was also the origin of the "build your own modular HP", called the K series where you pick and choose cpu boards, slot assemblies, etc. at time of order. He also mentioned that HP used to charge (at the time) $1400 to "clean the backplane". MeasureX found out that the CE's were just taking out all the cards and taking the unit to a car wash and spraying them with pressured water and then sun-drying them in the back of a closed up station wagon in the summer. So---- MeasureX just started doing it themselves and save a huge sum of money :) I found these tidbits interesting! Regards, Jay West