Donald Leo Dietmeyer, 93, passed away peacefully in his sleep on February 13, 2026, in Madison, Wis. The only child of Henry and Erna (Zastrow) Dietmeyer, he was born in Wausau, Wis., grew up among many cousins, and was a 1950 graduate of Wausau High School, where he was in the radio club and the curling club. A chance encounter sparked his interest in radios, then in electronics, launching his lifelong passion for electrical and computer engineering.

Don’s early interest led him to ham radio, call sign W9HHE, and his basement space crackled with the sound of radio and the smell of pipe tobacco. He tried his hand at wine and beer making with results that made for good stories. A man of exceptional kindness and generosity, he was a legendary gift-giver, changing the lives of those close to him and many people who will never know their benefactor. In his quiet Midwestern way, he took great pride in the accomplishments and exploits of those dear to him. Don lived his life focused on the simple things - the comforts of home, a good piece of pie, spending time with his children and grandchildren, listening to classical music, and researching his family heritage. Don was an immovable fixture at every family holiday, finding exceptional joy in celebrating Thanksgiving and Christmas. He was present for celebrations and adventures of all kinds, including every grandchild’s high school graduation, many weddings and ceremonies, concerts, and games. His excellent sense of humor stayed with him to the last, surprising the hospital staff with his quips. His jovial laughter will be forever missed, as will his bear-like hugs.

Don attended the University of Wisconsin-Madison, earning his Ph.D. in Electrical Engineering in 1959. He served on the faculty in the department of Electrical Engineering, later Electrical and Computer Engineering, for 40 years, 1958-1998, and was a Professor Emeritus thereafter. Don loved teaching; he was known to have high expectations, especially in the digital design lab, the subject dearest to his heart. He also served as an Associate Dean of the Department for 12 years, 1983-1995, where he was known for helping students out of tight jams that were often of their own making. While his career was filled with many accolades and accomplishments, he was most proud to have authored the textbook “Logic Design of Digital Systems” in 1978 and the CONLAN Report in 1983. His work played a significant role in formalizing and spreading digital systems education during the formative years of modern computing. His textbooks and teaching methods helped define how digital logic and computer hardware design were taught for decades.

Don was preceded in death by his loving wife and partner in adventure, Carol White Dietmeyer. Married for 63 years, together they enjoyed good times and good food with family, friends, and neighbors, celebrations of all sorts, and gardening. They traveled the world, taking over 30 trips, including to the 1996 Olympics in Atlanta. For years they were active in community theater; while Carol acted and directed, Don ran the lights, built sets and did whatever technical tasks were needed.

Don is survived by his four children, Karl (Cheryl) Dietmeyer, Elizabeth (Charles) Johnson, Anne (Daniel) Engbring and Diana (Thomas) Jacobs; six grandchildren, Laura (Evan) Ferree, Karla Peters, Erik Johnson, Erin (Eric) Johnson, Sean Johnson and Adam Engbring; and three great-grandchildren, Caroline, Jesse and Emmett.

Don will be remembered and his abundant life celebrated at GUNDERSON EAST FUNERAL AND CREMATION CARE, 5203 Monona Drive, Madison, Wis., at 11 a.m. on Saturday, March 7, 2026. Visitation will be held at the funeral home from 5 p.m. until 7 p.m. on Friday, March 6, 2026, and also from 10 a.m. until the time of the service on Saturday. Burial to follow the service at Blooming Grove Cemetery, Madison, Wis.

The family thanks the staff of St. Mary’s Hospital for their exceptional care of Don in his last days. In lieu of flowers, donations may be made to Wisconsin Public Radio, http://wpr.org/donate (enter ‘In memory of Don Dietmeyer’ in the comments). Online condolences may be made at www.gundersonfh.com.

This is W9HHE signing off. DE W9HHE 73 SK

Gunderson East

Funeral & Cremation Care

5203 Monona Drive

(608) 221-5420

Don Dietmeyer

November 20, 1932 - February 13, 2026

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