A reader who is a chip architect told us today that finding processor serial numbers (PSNs) on .25 micron Pentium IIs is not necessarily easy. (Story: Unique serial number exists on all .25 micron Intel chips) He said:"The bus multiplier is in that same PIROM [as the serial number] and while there is an interface to the PIROM it isn't accessible without some fancy hardware work. I can confirm your other source is correct [about processor serial numbers being in .25 micron PIIs.]" He added: The serial number and bus multiplier value (among other things) is written into the PIROM after the chip has been bonded out/packaged. The testing unit determines what the speed of the processor is and then writes the serial number information along with bus multiplier into the PIROM. A simple mistake in the test software would give the wrong value to the PIROM bit that allows the serial number to be read by the CPU." Tricky, but not impossible. Let's see what the rest of the week brings. Meanwhile, Intel's competitor, AMD, is keeping remarkably quiet about whether it will use PSNs in the future. It does have a statement on its Web site saying the idea itself is not a particularly bad thing. (Story: AMD wavers over chip security ID) We suppose it's waiting until all the fuss dies down before it makes its announcement. ®