I’ve installed Debian Bullseye on BBB to use the board for some normal desktop tasks. Flashed to the eMMC. It seems to have not enough space for simple operations i.e. “apt-get update” , or installing mc or some other packages (lean packages). Are these 4 GB to small for the system? Can I extend it to a SD card? So, I couldn’t find some important files, i.e. the “mc” couldn’t be found anyway, nor a alternative package. I remember that mc exists on BBB in former installations (debian 7.X i.e.) 
For normal ‘xfce’ desktop tasks use a microSD, and leave the eMMC blank…
mc = Debian -- Details of package mc in bookworm
Regards,
Thank You, of course, it seems the only way with this board (got it ca. 2016). I’ve studied the documentation from BBB, the “SD” card isn’t specified more detailed. So, is that max 32 GB capacity (raw)?
Nope… that’s the max SDHC spec, SDXC bumped it higher, with new ‘faster’ interface speeds, speeds the am335x doesn’t support… But the new size works fine, at older SDHC speeds…
Regards,
Thank You, Robert, looks good for me. Speed isn’t the reason, because the BBB isn’t a racing car, but SD cards like it to bite the dust without warning. A 32 or 64 GB card is enough for my purposes.
Regards, Ernst D