It could be, as in the case of the adapter, a transformer. It could also be a capacitor. I don't know how they make sound, but when I used to turn off my old Leading Edge, there was a high-voltage Cap that would make a loud *Chirp!*, then whistle, and the whistle would die down in a few seconds. It did the same thing when it was turned on, but backwards. It would start out as a soft whistle, get louder, then disappear, as the sound probably went out of the range of human hearing. It sounded sort of like when a computer would power up in an old Sci-Fi movie. Is the computer otherwise working fine? if it is, and there's no smoke or crackling sounds (like heating of coils or other components) after it's been on for a while, I wouldn't worry. Is it a constant, high-pitched whistle? Not being familiar with the Osborne 01, dose it have a built-in CRT? It could be that that's whistling. Try booting it with the CRT and control board (the thing with the high voltage transformer with the wire going to the side of the CRT) TOTALLY disconnected, and see if it still whistles. If it doesn't, then you've found the problem. As for fixing a whistling CRT, I haven't figured it out, yet (If anybody knows how, could they please tell me?). The only problems that I've seen the whistling do is possibly make your ears hurt. My current solution: wear ear plugs when using my Tandy 1000. -- -Jason (roblwill(a)usaor.net) ICQ#-1730318 ---------- <classiccmp(a)u.washington.edudastar(a)siconic.com ---------------------------------------------------------------------------- ---