Waltham Mr. Walter T. McDonald of Waltham died Tuesday, September 23, 2003 at his home. He was 55. Born in Newton, he was the son of the late George J. and Irene F. (Costello) McDonald and he was raised in Brighton where he lived before moving to Waltham 19 years ago. He graduated from Boston Latin School in 1966 and from Northeastern University in 1971. He also earned a masters degree in computer science from Northeastern. He worked as a diagnostic engineer for Nortel Networks in Billerica and before that held the same position with Codex Corporation of Mansfield. He was also a member of the Boston Latin Alumni Association and the Friends of Saint Jude in Waltham. He leaves his wife, Anne Marie C. (Brown) McDonald; his children, Matthew J. and Kathleen A. Katie McDonald, both of Waltham; one cousin, Michael Conti of Swampscott; his father-in-law, James Brownie Brown of Watertown; and his sisters-in-law, Kathleen Butterfield of Natick, Geraldine Gerry Brown of Medford and Christine Brown of Marlboro. He was also the son-in-law of the late Felicia Ann (Sallese) Brown. Relatives and friends are invited to attend the Funeral at 9:30 a.m. Friday from The Joyce Funeral Home, 245 Main Street (Rte. 20), Waltham followed by a Funeral Mass in Saint Jude Church, 147 Main Street, Waltham at 10:30 a.m. Burial will be in Saint Patricks Cemetery, Watertown. Visiting hours are Thursday 2-4 and 7-9 p.m. Donations in Walters memory to Saint Jude School, 175 Main Streeet, Waltham, MA 02453 would be appreciated.