F401 Nucleo Espruino Question

Thanks very much for the replies all!
I am getting a better feel for these forums now and I better appreciate that I am working on an "Unofficially supported board" and that support for these Nucleo boards will of necessity be a lower priority and any help that some (especially Gordon) provides, 'pulls' help from
Espruino/Pico support/issues. I have ordered a bunch of Pico boards and am rather impatient so wanted to get playing with Espruino JS ahead of their arrival.
OK, onward!

Are you using an NucleoF401RE or an NucleoF411RE?

I have both, but have only been playing on the F401 so far

Have you updated your firmware from st.com?

Yes, basically followed the instructions on the F401 page.

I decided to start from scratch. I downloaded fresh copy of F401 firmware from ST and did the ST-Link Upgrade to V2.J23.M6 (again) just in case.
I downloaded Espruino 1v71 (again) and copied espruino_1v71_nucleof401re.bin to the Nucleo.
I pulled the USB cable and then re-inserted it, and attached to it with the Chrome Web App.
Here is my session:

> // I will do a reset() here, sometimes things get overwritten with strange characters...
=undefined
ª¹¥¹5
 _____                 _
|   __|___ ___ ___ _ _|_|___ ___
|   __|_ -| . |  _| | | |   | . |
|_____|___|  _|_| |___|_|_|_|___|
          |_| http://espruino.com
 1v71 Copyright 2014 G.Williams
> // yes, the reset() was overwritten. Now I will do the setWatch() and save() it.
=undefined
Uncaught SyntaxError: Got ?[128] expected EOF
 at line 1 col 1
 // yes, the reset() was overwritten. Now I will do the set...
 ^
>setWatch(function (e) {  console.log(getTime()); console.log(e.time - e.lastTime); },
:  "C13", { repeat:true, edge:'falling', debounce : 10 });
=1
>save();
=undefined
Erasing Flash....
Programming 86016 Bytes...................................­........................................­............
Checking...)Done!
> // now i will do a 10-second test using the button...
=undefined
Uncaught SyntaxError: Got ?[128] expected EOF
 at line 1 col 1
 // now i will do a 10-second test using the button...
 ^
176.18122399999
NaN
178.09457523809
1.88026453571
> // now I will do a 60-second test...
=undefined
200.72823180952
5.64045157142 // edit: ignore this number. I screwed up a 60-second test prior, phonecall.
212.17027785714
11.40336201190
>

Those comments I typed in as I went. You will notice I get 'funny stuff' going on, perhaps this is a clue that I haven't a clue and/or I have bad hardware/firmware/something.

But once again, you can see that both tests took about 5.25 longer than "computer" time would indicate.

I don't know (yet) how to ask the Nucleo what clock speed it is running at.