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Old September 22nd 04, 01:13 AM
P2B
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geos wrote:
hello,

after some summer break I come back to the idea of modding my old p2b-d.
I reviewed the document here http://tipperlinne.com/p2b-ds150.htm and
want to make myself sure wheater the connections between pins are as
follows:

http://www.geocities.com/qroobas/ds-before.jpg


No, that's incorrect.

The leftmost pin (1) on all FSx jumpers is connected to Vio (3.3v) and
the rightmost pin (3) to ground. The middle pin (2) is connected to the
corresponding FSx input of the clock generator chip via a 10K ohm
resistor, so you get a logic '1' applied to the clock generator's FSx
pin when the jumper is set 1 - 2 and logic '0' when the jumper is set 2
- 3.

I would use 2-pin FS3 instead of 3-pin if the third pin, the rightmost
one, is unused. I would appreciate confirmation of these connections by
the author or Paul or somebody, who has done such modification.

thanks,
geos


The clock generator has an internal pull-down resistor to ground on FS3
(unlike FS[0-2], which have an internal pull-up), so a 2-pin jumper
(pins 1 & 2 only) will work, but it leaves the 10K ohm programming
resistor and attached wire floating when the jumper is removed - which
could theoretically introduce noise on the PCI clock signal. Note that
FS3 changes function from an input during reset to a clock output during
operation.

I follow the clock generator chip manufacturer's recommendation and
install a 3-pin FS3 jumper.

P2B