Martin Odersky, the creator of Scala and javac, was born in Germany but received his PhD in Zurich, at EHTZ, under Wirth's supervision[1]. Odersky is now a professor in Lausanne at EPFL [2].
[1] https://en.wikipedia.org/wiki/Martin_Odersky
[2] https://people.epfl.ch/martin.odersky/bio?lang=en&cvlang=en
In terms of companies, here's a few of the best known I'm aware of:
An old infamous one:
* https://en.wikipedia.org/wiki/Crypto_AG
And a couple of major international ones:
* Logitech (founded in Apples, Vaud)
* STMicroelectronics (headquartered in Geneva; though it was a merger of a French and an Italian company)
And a new but still quite well known security hardware one:
* Silent Circle (security hardened smartphones)
But as other have pointed out, in software/hardware Switzerland is doing best in R&D, not least because of the high salaries, and a lot of CS grads will also end up going into jobs in companies that are not necessarily hardware/software companies but that need a lot of CS talent (e.g. banks, high tech manufacturing).
Some names you might recognize:
* Niklaus Wirth (Pascal, Modula-II, Oberon etc.; retired professor at ETHZ)
* Jurg Gutknecht (Oberon; EHTZ)
* Erich Gamma (one of the "Gang of Four" behind the Design Patterns book; co-wrote JUnit; studied at University of Zurich)
* Urs Hölzle (Google SVP of Technical Infrastructure at Google; studied at ETHZ)
A lot of people can also be traced back to Wirth. E.g. Andreas Gal that did his thesis on trace trees for JIT compilation is German, and did his thesis at UC Irvine, but his advisor was professor Michael Franz who did his thesis on runtime code generation before Java was released under Niklaus Wirth.