Access Anomalies

Using Delphi 3.0 & corresponding BDE 4.51.  Using Paradox  & native

TBlobField.IsNull works correctly with Paradox.  The same always returns
false with Access, even if the field was "left empty" during creation of
the record.

How can I check for data in a TBlobField in an Access table?  Where can I
find information telling about other exceptions, peculiarities, etc. when
using the native Access driver?