as said in previous post:

There is no automatical wrap from line 1 to line 2.

Check this document:
http://personal.telefonica.terra.es/web/x-rob...i44780.pdf

see page 11:


Case 1: When the number of display characters is less than 40 X 2 lines, the two lines are displayed
from the head. Note that the first line end address and the second line start address are not
consecutive. For example, when just the HD44780 is used, 8 characters X 2 lines are displayed. See
Figure 5.
When display shift operation is performed, the DDRAM address shifts. See Figure 5.



regards
Patrick