A few minor comments on a pretty comprehensive and well written article. Although TEMPEST is closely related to EMI shielding, remember that TEMPEST is concerned only with *information bearing* radiations, not interference. In particular, the switching power supply, a potentially prodigious source of EMI, is not a significant TEMPEST issue because power supply emissions carry little if any information. (Varying loads might cause minor modulations of switching frequencies, etc, but this is probably something that only the paranoid "covert channel" types worry about. Maybe you coull tell when the floppy drive motor starts and stops, but I doubt you could do much else.) Who knows, cutting down on power supply radiation might make it easier to extract information from the emissions that remain, because of the jamming effect of power supply noise. But don't let that stop you. It's your duty to your neighbors to emit as little RF noise as possible. When I lived in New Jersey, I learned to my chagrin that my two PC clones made my next door neighbor's AM radio useless. Only 25 miles from New York, he was unable to listen to WABC, a 50KW clear channel AM station! The problem disappeared completely when I installed some inline AC RFI filters in the power supplies. Since we shared a pole transformer, I theorize that the noise was conducted from my computer to his radio directly over the power lines. Which brings me to my next point. I have not seen *any* clone-grade PC power supplies with adequate power line filtering. They have a minimal LC lowpass network on the power supply board itself, but this is usually inadequate. Whenever I buy a new power supply, the first thing I do when I get it home is to replace the IEC power connector with an integrated, shielded power connector/RFI line filter. These devices are widely available for several dollars from electronics surplus houses and amateur radio "hamfests". I also use power cords with built-in ferrite "lumps" but these are probably harder to find (one particular hamfest vendor had a lot of them a few years ago, but I haven't seen them since.) Modern monitors are *much* better shielded than the early PC monitors, especially those no-name Korean or Taiwanese copies of the original IBM PC monochrome monitor. If you have the misfortune of owning one of those old monitors, as I do on one of my systems, chances are the lion's share of its emissions are coming from the +70V power lead that runs from the main circuit board to the video output stage on the base of the CRT. (Note! Do NOT confuse this with the high voltage lead going to the anode of the CRT!) The +70V power line to the video output driver acts as an antenna for radiated video signals that can be *quite* strong. I suspect that the reports we've seen of successfully picking up the image on a computer display were taking advantage of this. To fix the problem, just replace the plain wire with a piece of shielded coax, bypass the ends with .01 or .1 uF capacitors of sufficient working voltage, and ground the shields to circuit board ground on both ends. Phil