Ensure that the CCP and ls don't change drive when listing a directory.
This avoids issues where the current drive according to the BDOS doesn't match the current drive according to the CCP, which can make odd things happen.
Fixes: #151
Fixes: #113
Fail with a hard error when trying to write to a full disk.
Previously it would just keep searching up off the end of the bitmap and trying to write to out-of-bound blocks.
This avoids issues where the current drive according to the BDOS doesn't match the current drive according to the CCP, which can make odd things happen.
Fixes: #151 Fixes: #113
Previously it would just keep searching up off the end of the bitmap and trying to write to out-of-bound blocks.
Fixes: #170