Marc J. Rochkind was a programmer at Bell Telephone Laboratories who built the Source Code Control System (SCCS) while working on a large telephone-switching software project there in the early 1970s. SCCS was the first widely used system for keeping the full revision history of source files, and Rochkind is credited as its author.
Rochkind described the system himself in “The Source Code Control System,” published in IEEE Transactions on Software Engineering in December 1975. The paper, listed under his name in the ACM Digital Library record, explains how SCCS stored every version of a module, controlled who could update a file, identified each released version by number, and recorded who changed what, when, and why.
The problem Rochkind set out to solve was practical: on a project with many programmers and many modules, copies of source files multiplied and it became hard to know which version was current or how a file had reached its present state. SCCS answered that by keeping a single controlled history per file instead of a pile of loose copies.
The design ideas Rochkind introduced - a tracked history per file, checkout and check-in of revisions, and a record of authorship for each change - became the template that later systems built on. RCS, CVS, and the version-control tools that followed all trace back to the basic model SCCS established.