I have a sco unix server that I'm unable to loginto error NOTICE:HTFS :No space on devhd (1/42)?
You need to boot into single user mode from tape, or CD, mount the disk and remove some files to make room on the disk. Then you should be able to rreboot and log in normally
How to open .sco files?
Just to clarify, I'm assuming the .sco file type you're talking about is the kind used for objects in the game league of legends. It turns out that this is a proprietary file type created by Riot games, and they have not released the specifications. Some smart person has created a converter that will convert a .sco to a .obj, which can be opened by just about any 3D software. I recommend blender for editing 3D models (free, blender.org). The converter can be downloaded at http://www.leagueoflegends.com/board/attachment.php?attachmentid=1343&d=1251072626. The file is a zip and inside is lol2obj_v1.0.exe. Just drag the .sco file onto lol2obj_v1.0.exe and it will create a .obj in the same folder as your .sco. Open the .obj with blender. Unfortunately, there is no way to convert .obj BACK to .sco, so any modifications can't be ported back into the game.
How many types of operating systems and what are they?
There are three main operating system that exist and are popular in todays world. Windows, OsX, Unix. Windows has many differnt versions that were built in a progressive maner each to improve the previous or to provide a different perpose. For example Windows server, Windows tablet, or Windows Vista. Os X( os 10) has it roots in Unix and then developed into a progressive os similar to windows only a lot more stable and is vendor specific. Unlike Windows OsX only works on an apple computer with out modification that is. Unix has developed into is own monster and in not progressive but rather has grown into distrobution. The main three are basic Unix, Bsd, and Linux. Linux has grown in popularity in the last few years. The most popular distrobution as of now would probably be between Ubuntu, Red hat, and Suse linux. The most popular Unix you will find is probably Novell, and the most popular BSD is Open BSD. There is also DOS but it is old and can only has a command interface. To answer you question there are thousands of operating systems. to many to count. you should check out distrowatch.com