Due to an error (as shown below) in the Quartus® II software versions 10.0 and 10.0 SP1, the ALTMULT_ACCUM and ALTMULT_ADD MegaWizard Plug-Ins allow incorrect configurations when targeting Stratix® IV devices, which do not support multiplier-adder megafunctions using logic elements.
To work around this issue, open the ALTMULT_ACCUM or ALTMULT_ADD megafunction and select the Extra Modes tab of the Parameter Settings page. For implementation, choose the Use the default implementation or Use dedicated multiplier circuitry options instead of the Use logic elements option.
The Use logic elements option is scheduled to be disabled for Stratix IV devices in a future release of the Quartus II software.
Error: MGL_INTERNAL_ERROR: Assertion failure inside rtl_body at <Quartus II installation directory>/cbx/cbx_altmult_add/cbx_altmult_add.cpp:2085
CAUSE : The condition in MGL_ASSERT () failed.
Error: Assertion error: The current megafunction is configured for use with the clear box feature and cannot be used when the clear box feature is disabled