Naturally, with his enquiring mind and eye, the potential of new technology was attractive, and in 1973, he joined Linotype-Paul, the branch of Linotype involved in developing film-setting systems. The possibility of extending these to non-European scripts, many of which had been too complex for hot-metal Linotype, was an agreeable challenge. In addition to Arabic, he also produced two related Hebrew types, which were credited to "David Silver" (I am not sure why a pseudonym was required).
The books that he wrote after he retired are well worth reading. Letters of Credit took a series of well-known letter-forms (none, characteristically, of his own design), and subjected them to a detailed analysis in terms of form and function. His style was spare and concise, but always clear; virtues even more marked in The Typographic Scene, into which at least some subjective detail, even a little autobiography, was admitted.
Any conversation with Tracy was a delight. His wit, original turn of phrase, but above all his clarity of mind, the honesty that permeated everything he did or said, made meetings something to look forward to. Our last long conversation, on the origins of "Times New Roman", was perforce on the telephone. It was unfinished, the answers to the questions under discussion still elusive. Had he lived, I am sure he would have found them - at least, there would have been another meeting, and a chance to exercise that selfless but lively intelligence, to feel again the warmth with which he greeted all the people and problems that came his way.