That would be a waste of money (something MB manufactuers are loathe to do). The battery is needed anyway for the RTC. Keeping an additional chunk of RAM alive is virtually free. What do you suggest, an expensive double-layer capacitor? Flash would also be less approprate than EEPROM technology.
Best regards, Spehro Pefhany
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"it\'s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
Not out of date. It *is* cheaper for *large* memory sizes, but...
1] In your reference above, see the "sector erase" issue with flash. EEPROM can be changed one byte at a time.
2] The amount of memory required for BIOS *settings* (as opposed to the BIOS *program*) is quite small. Early ones were 64 bytes with the first 16 used for the RTC. Newer ones are probably several times that size, but still tiny compared to even a small flash memory. The smallest flash memory out of the 2200+ different types that Digikey carries is 256K bits (there's one shown erroneously as 1K, but it's actually 1M). They go up to a rather staggering 8G bits. EEPROMs, OTOH, start at 128 bits (16 bytes) and go up to about 1M bits. So, not only do you have the sector erase issue, but most of the memory would be wasted.
Of course some settings *are* stored in flash, in a sense, since the factory default settings are part of the BIOS program, which is generally stored in flash these days. One could write a BIOS to store the settings in the large program flash, if it has the ability to boostrap, but that could result in a dead motherboard and an angry customer if the power failed or a crash occured during the routine writing of values, so I think most engineers will not be overly eager to invite that kind of problem to the door. Even if it happens only rarely, it's an extremely serious problem to the user.
Best regards, Spehro Pefhany
--
"it\'s the network..." "The Journey is the reward"
speff@interlog.com Info for manufacturers: http://www.trexon.com
One could argue that even the RTC is almost not needed in most desktop PCs now, they could get the time direct off the Net. Then you do have some savings - no pesky battery, and no CMOS ram.
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Regards,
Adrian Jansen adrianjansen at internode dot on dot net
If you object to the coin cell, remove it and wire in a series pair of AA cells (assuming the coin is 3v, of course). The last time I did this mod was in 1999, to an IBM PC-AT. BIOS was still fine yesterday when I used that machine to assemble some MC68705 code.
Agreed. Heartily! That breed of assumption is too common, causes no end of frustration/problems. Of the half dozen PC's I use, only one ever connects to the web.
My NEC 486 laptop's lithium battery's shot, and the battery in my Pentium II-366 MHz laptop is starting to go on the fritz...
On a positive note, though, I finally got my PII laptop to remote-control my main desktop machine last night (using vnc... that Microsoft Remote Desktop Connection didn't work for me)
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