Leonard H. Tower Jr. was a founding board member of the free-software-foundation at its incorporation in 1985 and became the organization's first full-time employee. His technical contributions centered on the early development of GCC, the GNU Compiler Collection — specifically work on the rewrite of the compiler from the Pastel language to C, which was essential to making GCC portable and self-hosting.
The GCC rewrite from Pastel to C was a critical moment in the gnu-project's technical history. stallman had designed the original compiler, but the choice of implementation language had practical consequences for portability and adoption. Tower's work on this transition helped establish GCC as the free software compiler that would eventually support the full GNU system and, later, the GNU/Linux combination — the gnu-linux-naming controversy reflects how foundational the GNU tools including GCC were to the resulting system.
As the FSF's first full-time employee, Tower represented the institutionalization of what had been stallman's individual project. The founding-gnu-and-fsf-1983-1991 era required people willing to commit their careers to an organization that had no guaranteed future and was pursuing goals that the commercial software industry considered quixotic or threatening.
Tower left the FSF in 1997, during the transition to the gpl-and-linux-era-1991-1998 period when the movement was expanding rapidly and the tensions that would produce the open-source-definition-schism were beginning to surface. His departure marked the end of a chapter in the FSF's early institutional history. His role in the founding cohort alongside robert-chassell, harold-abelson, and stallman himself shaped the organization's early culture and governance.