mainframe
MULTICS
There is no correct answer without qualifying which multiuser systems are being discussed. All modern operating systems have inherited traits and abilities from other older multiuser systems. There are multiple multiuser operating systems currently in use. IBM has their mainframe system (Z/os) as well as IBM i, both multiuser systems are unique from each other and from other systems. IBM also has AIX, a descendant of unix. Current unix systems go back to the original proprietary AT&T unix implementation in the 1970's and 1960's. Unix itself was modeled after a multiuser system called Multics. Linux was modeled after unix but written independently of it. Microsoft Windows NT was designed by Dave Cutler who brought his experience in developing OpenVMS with him. All other Microsoft Window implementations follow from that.
Almost all modern Operating Systems support peer to peer networking.
Galileo is known as the Father of Modern Astronomy, the Father of Modern Science, and the Father of Modern Physics. He is not None for anything.
Leonardo da Vinci is the father of modern helicopters.ANS 2 - Igor Sikosrki is the father of modern helicopters.
The father of modern Culinary is Auguste Escoffier.
Paracelsus is considered the father of modern toxicology. He was a Swiss physician, alchemist, and astrologer who is known for his contributions to the understanding of the effects of chemicals on biological systems. His famous quote "The dose makes the poison" is a fundamental principle in toxicology.
Almost all modern computer hardware, including the Macintosh range of computers, and operating systems are multi-tasking.
Antoine Lavoisier is considered the father of modern chemistry.
Sir Ambrose Fleming: Father of Modern Electronics
No 'father of modern science' shouldn't be capitalized.
The "Father of the Modern Skyscraper" was Louis Sullivan.