The C language (Read Ritchie) unified that hardware world, making it possible to write portable programs that would be hardware agnostic. A C compiler was created for all hardware and this made it possible for a C code to run seamlessly on just about any device with a C compiler (remotely similar to the java virtual machine of today).
Just when people said it could not be done, he went ahead and did it. It was so simple, yet so elegant. Dennis Ritchie gave his contemporary programmers, a language that was structured, high level and could create system programs. Above all, he freed the programming language from the bonds of being the brainchild of academics or any other bureaucratic setup. This was an independent programming language, coming from a seasoned programmer.
This portability of the C language allowed him to rewrite the UNIX kernel in C and make use of all features of the then new, DEC PDP-11. Finally, he developed a portable operating system that would work across hardware, the operating system we know as UNIX today.
Dennis Ritchie and the DARPA Project
When Dennis and Ken started working together on the UNIX OS, it was a head-turner. The ARPA (Advanced Research Project Agency) took notice of them. ARPA was so impressed by the UNIX OS, they became their client eventually and Ritchie had never looked back ever since. The birth of the UNIX OS was streamlined with the birth of the Internet and this is regarded as one of the most beautiful phases of Bell Labs.