Power Supply Oddity

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I just noticed after a long, long time that the PC Health BIOS display for
my Biostar M7VIG motherboard reports 0v for the -5v rail.  The system works
just fine so I decided to look into it a little bit.  I discovered the power
connector on supply does not have a wire on pin 18 ( that is where the MB
manual says it expects -5v) so of course the BIOS was reporting 0v.

No one around here knows what the -5v might have been used for nor why the
manual calls for it on pin 18 when the it apparently lives happily without
it.   I remember that back in  TTL days, -5v was commonly used.

Can someone clue me in here?

Thank you

Re: Power Supply Oddity

Jack Gillis wrote:
Quoted text here. Click to load it
Negative substrate bias voltage for very old
memory chips. Nowadays any chip needing that bias
generates it on_chip, so -5V is redundant.

Re: Power Supply Oddity

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OK and I thank you.

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