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From: rbowman <bowman@montana.com>
Newsgroups: comp.os.linux.misc
Subject: Re: F2FS On USB Sticks?
Date: 22 Mar 2025 19:09:50 GMT
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On Sat, 22 Mar 2025 13:35:54 +0000, The Natural Philosopher wrote:

> The PICO has no filesystem. IN use you hold a button down while powering
> up and it's Flash presents itself as a USB drive. You copy a special
> binary file of compiled code onto that 'drive', and it reboots and runs
> it..

Okay, you hold down BOOTSEL when plugging it into the USB. Then it shows 
up on Files as RP2350.  If you click on that you see INDEX.HTM and 
INFO_UF2.TXT. If you look at Properties it reports 2 items totaling 305 
bytes and 134.1 MB free. 

df -Th /dev/sda1
Filesystem     Type  Size  Used Avail Use% Mounted on
/dev/sda1      vfat  128M  8.0K  128M   1% /media/xxxxx/RP2350

Then you can

cp blink.uf2 /media/xxxxx/RP2350/

and, lo and behold, it starts blinking and vanishes from the file system!  
I'm lazy so after it blinks 20 times it calls 

reset_usb_boot(0, 0);

and miraculously reappears mounted.  How does it do all this without a 
file system known to Ubuntu? I won't even ask why after copying the 
CircuitPython uf2 it reboots mounted as CIRCUITPYTHON and you can copy .py 
files directly. 

My comment had nothing to do with the programmatic use of the flash 
memory, only how the Pico presents as a mass storage device.