> How Fast can a typical PORT Pin of a PIC Micro Switch from
> Low to High or vice versa

That spec is in the datasheet. In the 18F1x20 d/s it's 10ns typical,
25ns max for both rise and fall (longer max for LF)

For Scenix it's shorter than that, perhaps 4-5ns. Waveform at 50MHz

http://www.sxlist.com/techref/scenix/an_sc_01.gif

Actual pulse width, as detected by a PIC depends on the VL / VH
thresholds

> i.e. if a Pin is Initially Low... and if I switch the PIN high and set it
to
> Input immediately.. and read it back in the next instruction.. Will I be
> able to read the expected high level 1...

Hmmm. For 18F the i/p is PORT and o/p is LAT, which are separate

For 10/12/16 you might see it. If what you want to do depends or not
on whether this '1' is present is perhaps best found by experimentation

> say if I was running the PIC at 40MHZ..

18F then ?

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