hello sir, still about the genpat stuff. I added the DECLAR arguments you told me to add, however and the genpat instruction went well. After that, using the instruction "more halfadder.pat" resulted in the ff statements: note the unprocessed pattern stuff . . Removing tmp files ... bash-2.02$ less halfadder.pat -- description generated by Pat driver v107 -- date : Tue Oct 23 09:24:19 2001 -- sequence : halfadder -- input / output list : in vdd B; in vss B;;;;;; in a B;;; in b B;;; out sum B;;; out carry B;;; begin -- Pattern description : -- vv a b s c -- ds u a -- ds m r -- r -- y -- Beware : unprocessed patterns < 0 ps> pat_0 : 10 0 0 ?0 ?0 ; < 1 ps> pat_1 : 10 0 1 ?1 ?0 ; < 2 ps> pat_2 : 10 1 0 ?1 ?0 ; < 3 ps> : 10 1 1 ?0 ?1 ; end; bash-2.02$ Does the statement: "beware - unprocessed patterns" mean that a correct simulation could not be achieved? how do I correct this problem? John DB --------------------------------- Do You Yahoo!? Make a great connection at Yahoo! Personals.