a friend wrote me and asked, In the end game if you have only a King left and I have a rook and King .... is there a limit to the number of moves it takes to checkmate?  I personally have never heard of any time limit but the fellow prisoners he's playing have said that there is a 13 move limit or its a draw. another has said 50 moves or a draw.  His opinion is that there is no offical limit but perhaps different tournaments may run things differently.   where might I find concise rules on this to send him since appearently they do not have access to the internet.  thanks

I believe the 50 moves and draw has to do with pawns having to move in 50 moves

I believe that when there is only a king rook vs a king sure there is a 50 move rule to checkmate but usually you never use the 50 moves to mate. If you got taught the endgame correctly, the most I've ever seen is about 30 which is the real long way. I assure you that you don't have to make 13 moves to mate - that's completely wrong. In some cases there are a time limit. In 30-40 moves if it is clear that you are going nowhere with the position and you have no clue how to win, I'm pretty sure the officials will call it a draw instead of playing out the 50 moves.

Copied and pasted from wiki:

The fifty-move rule in chess states that a player can claim a draw if no capture has been made and no pawn has been moved in the last fifty consecutive moves (fifty moves by each side). The intended reason for the rule is so that a player with no chance to win cannot be obstinate and play on indefinitely, or seek a win purely due to an opponent's fatigue. All of the basic checkmates can be accomplished in well under fifty moves.

In the 20th century it was discovered that some positions of certain endgame can only be won in more than fifty moves (without a capture or a pawn move). The rule was changed to include certain exceptions in which one hundred moves were allowed with particular material combinations. However, more and more exceptions were discovered and in 1992 FIDE abolished all such exceptions and reinstated the strict fifty-move rule.