Browse Prior Art Database

Computer Power on Hour counter lock Disclosure Number: IPCOM000032198D
Original Publication Date: 2004-Oct-26
Included in the Prior Art Database: 2004-Oct-26
Document File: 2 page(s) / 50K

Publishing Venue



Today warranty is by time length (one year, two years, etc.). However failures are by power on hours (POH). Therefore it is interesting if computer manufacturers to change warranty to a 2 year or 20,000 POH concept, or have different warranty rates for different POH's. To do this requires a method of tracking power on hours that can't be changed or rolled back by the end user.

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Computer Power on Hour counter lock

Smart card are now very inexpensive (about 30 cents) and very thin (credit card thickness). They can store motherboard serial number and POH information. The motherboard processor can read/write the information by physical contact or touch. The desktop or laptop mechanicals are designed in such a way that the smart card is fitted into a recession in the bottom cover. The motherboard sits on top of the smart card and by mechanical interlock physically touches the pads on the smart card (See Fig 1).

During system startup or POST the processor checks to see if the motherboard has been changed. This is a critical condition as if we replace the motherboard we need to update the motherboard POH to match the original system POH which are stored on the flash card. We can do this by checking the motherboard serial number in smart card. If different motherboard was replaced and the POST will than copy POH value from smart card into EEPROM on motherboard.

If the same (Normal condition) the POST will update smart card to motherboard POH value. The POST than locks smart card so no other changes are possible thereby preventing the user from changing the POH counter on the motherboard. The system than boots. A System Management Interrupt routine (SMI handler) updates POH in EEPROM on memory every x seconds during normal operation policy driven. On the next boot the POST will than be able to update the smart card POH counter.

Fig 1.


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