I am using iverilog v0_6_1. When it encounters the following conditional assign. assign DR_DATA = DR_READ ? 64'dz i : DR_DATA_REG; I get the following error: PARSING INPUT ... 151: unmatched character (') drv_iv.v:151: parse error drv_iv.v:151: error: syntax error in continuous assignment make: *** [test_iver] Error 2 This works on vcs but not here anyone know why. Lonnie