I came to know about this just a short while ago. For those who are unaware who Dennis Ritchie is, he was co-inventor of Unix Operating System (OS) along with Ken Thompson and inventor of ‘C’ language. No need to say these two revolutionized the use of computers and actually got the computers many levels close to researchers and software developers. After these were developed software engineers were actually able to interact with the computer live , to write, prototype and test the programs, which we really take for granted today. Prior to this OS and language, it used to be  high level programming language like Fortran and batch processing of the programs , which one can submit to a mainframe or mini-computer and wait for the output, when a systems analyst runs them on the slot/time allocated to the user! Much like a big Telescope like Hubble is booked by scientists on a time-shared basis. I still remember how we had to stand in line for two hours early morning 4 a.m to get a half-hour slot on a terminal to work on projects on an IBM mainframe computer at IITM. Prof. Mohan can vouch for this.

Dennis Ritchie was instrumental in designing an OS which is much simple and affordable to be developed on small computers and yet enabled multi-user and multi-tasking environments to make the best use of them. Today we have millions of computers and systems and soon to be billions  of iOS , android and other mobile devices which are all based on this simply amazing operating system, which is the brainchild of this person.  RIP Dennis Ritchie.

Here is a small video where Dennis himself spoke about the Unix OS!