Wesley A. Clark, a physicist who designed the first modern personal computer, died on Monday at his home in Brooklyn. He was 88.

The cause was severe atherosclerotic cardiovascular disease, according to his wife, Maxine Rockoff.

Mr. Clark’s computer designs built a bridge from the era of mainframe systems, which were inaccessible to the general public and were programmed with stacks of punch cards, to personal computers that respond interactively to a user.

He achieved his breakthroughs working with a small group of scientists and engineers at the Lincoln Laboratory of the Massachusetts Institute of Technology in the late 1950s and early ’60s. Early on they had the insight that the cost of computing would fall inexorably and lead to computers that were then unimaginable.

Severo Ornstein, who as a young engineer also worked at Lincoln in the 1960s, recalled Mr. Clark as one of the first to have a clear understanding of the consequences of the falling cost and shrinking size of computers.