Now that I have played a little more with EDCW, I have detected an error on it. I have tested also the original program to discard bugs made by my modifications.
The problem is with the File Manager, after a while changing directory or drives and running applications, it simply refuses to load known files, and gives the error: "Invalid File Header".
Actually the only cure I see for this problem is to enter and exit of EPDOS, or hard reset the EP, as some information seems to survive to soft resets.
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On the other side, I'm planning to modify the drive selection on the File Manager to admit all the possible drives. It doesn't seems too difficult for me...
The idea is to open a prompt with only one character input, the letter of the drive. Only upper letters from A to Z will be possible, although lower ones can be converted to upper case form. Other characters will be refused.
Then the space saved from the old method menu can be utilized for the extra lines of code.