After the 1200-baud touch reboots the board into BOOTSEL, the upload tool (platform/tools/uf2_upload.cmd on Windows, uf2_upload.sh on Linux/macOS) copies the sketch's .uf2 to the BOOTSEL drive (RPI-RP2, or RP2350 later). If that drive is not mounted it tries picotool load -x, and it retries both for 15 s.

picotool needs a WinUSB driver for the RP2040's BOOTSEL interface on Windows, which the RP2040 boot ROM does not get installed automatically; users must run Zadig, which needs admin rights that students on lab PCs may not have. Found on hardware: every IDE upload failed at the last step on a Windows PC without Zadig. Copying to the drive works on any PC with no set-up. picotool stays as the fallback for machines where the drive is not auto-mounted (e.g. headless Linux with picotool's udev rules).

A batch file and a POSIX shell script need nothing installed and are easy to read and change. Windows uses a batch file, not a PowerShell script, because managed PCs may block PowerShell scripts by execution policy; the batch file only runs a one-line PowerShell command to look up the drive letter by volume label (which avoids "no disk" prompts from empty card readers). .gitattributes keeps .sh files LF and .cmd files CRLF whatever the machine's git settings.

Two small scripts to keep in step. A drive copy cannot verify the written flash the way picotool can; the board reboots when the UF2 transfer completes, and an incomplete file simply leaves it in BOOTSEL.