[NextStep]

I have (hardware?) problems with internal memory [dup thread deleted - MODERATOR]: cannot read or write from/to the READER partition of my SONY PRS-T1.
As a workaround I thought: maybe just use a sD-card and forget about internal memory for the time being.
So I inserted a FAT formatted sD-card (small, 256 MB). Connected my Sony PRS-T1. Due to memory errors it took several minutes to see the disks (only SETTING and READER). I saw this before.
Without starting Calibre the sD-card did not show, even after waiting for several minutes. After I started Calibre though it did show. Calibre first reports errors communicating with the device. This I expected from earlier experiences without having a sD-card in the Sony. Then Calibre sees the device: "SONY reader detected".

I could send books to the device from Calibre but after selecting a book and right-click I only see the option "Send to main memory". "Send to storage card A" and ".... card B" are grey. Could send several books to device without problems. These files end up on the external card !! (in my Linux PC as /media/ext_sd).
In the Device-icon of Calibre only the option "Show books on main memory of device" is shown. But after having copied several books, this option does not show any books: empty list.

When I disconnect and reconnect the reader Calibre reports this problem:
calibre, version 1.9.0
ERROR: Error: Error communicating with device
The SONY database is corrupted. Delete the file /media/ext_sd/Sony_Reader/database/books.db on your reader and then disconnect reconnect it. If you are using an SD card, you should delete the file on the card as well. Note that ....
etcetera (several errors/traceback in python files)

But the file /media/ext_sd/...../books.db *is* the file on the card. Calibre seems to think this is main memory, because it says: "If you are using an SD card, you should delete the file on the card as well".

When I delete the books.db file it is recreated after reconnect and Calibre still gives the same message about corrupted database (because of missing books.db in READER?)

I know maybe I'm asking a bit to much of Calibre: working with a device with a faulty memory....
But is it possible to let Calibre completely ignore the main memory and only access the sd-card for its database and books?