Which is not invalid user file name?

{QUESTION TEXT} A commonly used graphic format for the web is

The earliest calculating devices are

The commonly used standard data code to represent alphabetical, numerical and punctuation characters used in electronic …

The most frequently used instructions of a computer program are likely to be fetched from:

Why ABC is considered electro-mechanical computer?

What will be the command if yout want to copy ra.doc file that resides in the floppy disk into work sub-directory of har…

Which will not create a sub directory on disk?

IBM System/360 is