The origin of Unix trace in 1965 by Bell telephone laboratory,the General Electronic Company & Massachusetts institute of Technology.
Aim of that association was to develop an operating system that could serve a large community of users and allow them to share data if neeeded.
Danis Ritchie and Ken Thomson in 1969 create a first version of multiuser system Unix on computer PDP-7.
In 1971 Unix ported to PDP-11 with 512 KB disk.Then unix is a 16 KB system with 8kb for user program and upper limit of 64 KB per file,Unix was machine dependent.Ken create B language and rewrite Unix in this language,but it lack in real life programming.Then Ritchie shifted Unix to C language code which finally enable Unix to stand on any machine.
Hardware requirement of Unix:-
It has minimum 80 MB hard disk,4 MB RAM on a 16 bit microprocessor.Out of 80 MB ,40 MB eaten away by actual Unix files,10-20 MB is used as swap space,swap space is used when Unix falls short of memory .At such time it temperory stored in swap space ,the content of memory which are not currently required then shift back to memory.More the number of terminals more memory is required.As a thumb rule 0.75 to 1Mb should be present in host machine.
Salient features of Unix:-
1. Multiuser capability.
2. Multitasking capability.
3. It provide communication media.