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| Fig 7: Boot system that 'never dies'
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A major cause of motherboard failures with modern flashable BIOS technology is the interuption of the BIOS flash update. Many commonly update their BIOS version when a better one appears. During the period when the update is under way is the time of greatest risk to the system. This is because the program used to control the BIOS update is the BIOS that is itself being replaced. Mostly this works well, but on occasion there can be an unexpected interruption in power supply, a spike or other unforseen problem which stops the process. It often resets the motherboard, leaving a BIOS that is partly the new version and partly the old one. This mixture is usually fatal because the update process can no longer be re-started, or cannot complete the update any longer because the control software is now corrupted. This usually makes the motherboard useless, the only recourse being to send it back to the factory or replace it.
How does this system help?
By employing a piece of older technology (EPROM) with a copy of the initial system BIOS burned into it, there is always a good copy available to recover the system with. Failure of a BIOS flash update will not need to result in the loss of the motherboard, because the older BIOS detects the problem and re-flashes the EEPROM/flash RAM before booting the system. The flash update can then be attempted again as needed.
Won't the older technology create a bottleneck?
Not really (see Fig 7). When the motherboard resets, it begins by resetting the hardware switch so that the EPROM (which always works) begins the hardware setup. It's first job is to check the condition of the flash RAM (which the switch puts at another address in the memory map). If it checks out OK, the hardware switch is changed to put the flash RAM in its normal location. The BIOS then continues to boot the system normally. In this way, the EPROM should not be used for more than a few seconds after initial power on. Any bottleneck effects are limited to that brief period.
What if the flash BIOS does not check out OK?
This is where this system comes into its own. The choices open to the BIOS designer are:
1) Display an error message and automatically copy the EPROM to the flash RAM before booting.
2) Offer a choice between option 1 and re-attempting the flash update. Either way, the result is a recovery of what would otherwise be a dead motherboard, along with all the system downtime and reconstruction that implies.
What's the point of that?
Simple. Any motherboard fitted with this system will last its full service life and never be returned because of flash BIOS update failure. The risks of flash BIOS updating are effectively eliminated.
COPYRIGHT STATEMENT: This concept was originated by John Spencer Durham in September 2000, and posted on the internet on October 6 2000. Anyone with the means and desire to develop this principle into a commercial system is free to do so providing the originator is acknowleged by name along with the product, its packaging and manuals.PREVIOUS
