"A Computerized Backgammon Opponent" (from Vol. 1 No. 7) NEWGAMON is a computer program that allows you to playbackgammon against a computerized opponent. Though NEWGAMONcertainly will not win any tournaments, it is an aboveaverage player -- good enough to provide plenty of practiceand to keep you on your toes. I downloaded the program from a computerized bulletin boardservice (BBS) here in my home town. In its original form,the program did not actually play the game; it only keptscore while two human players participated. Imagaine mydisappointment when I found that out! I was really lookingforward to matching wits with the computer. So, to make a long story short, I added a new subroutine tothe program to allow the computer to become an activeplayer. If you already know how to play backgammon, you canskip to the last paragraph of this article. If not, here isa quick primer on how to play backgammon. Backgammon is played on a board containing 24 "points". Inthis game, each of those points (or positions) is labeledwith the letters A through X. Each player controls fifteenplaying pieces or "pips". In this game, you are assignedthe solid green pips, while the computer controls thespotted red pips. Your fifteen pips are scattered across the board as youstart the game -- 2 are on point X, 5 are on point M, 3 areon point H, and 5 are on point F. The computer's pips areplaced in mirror opposite positions. The object of the gameis to move all of your pips into your "home table" (for you,the region between points A through F; for the computer, theregion between points S through X) and then to move all ofyour pips off of the board before your opponent does. Movement is accomplished on each player's turn by rollingtwo dice. If you roll a 3 and a 4, then you can move onepip 3 spaces and another pip 4 spaces (or you could move thesame piece first 3 spaces, then 4 spaces). By the way, ifyou roll doubles, you get twice as many moves. For example,if you roll two 3's, you get to move 4 pips 3 spaces each.Movement proceeds in a "horseshoe" direction. You move yourpips from X to M, from M down to L, and from L back to A.The computer moves in the opposite direction (from A to X). You can move your pips onto almost any point. If the pointis empty, then you can move onto it. If some of your pipsalready occupy a point, you can move onto it. If the pointcontains one and only one of your opponent's pips, you canmove onto that point and "hit" your opponent's "blot" (moreon that later). If the point contains two or more of youropponent's pips, you CANNOT move onto that point; his two(or more) pips are effectively "blocking" that point. If you do move onto a point and "hit" an opponent's singleunprotected pip, his pip is moved "onto the bar". When aplayer has a pip on the bar, he cannot make any other movesuntil that pip is retrieved from the bar. You must roll thedice to re-enter a pip from the bar; for example, if youroll a 4 and a 5, then you could move a pip from the baronto the fourth or fifth point (labeled D or E). If bothpoints are blocked, then you are stuck and have to forfeityour move! Once you have moved all of your pips into your home table(between A and E), you can begin to "bear off" your pips (orremove them from the board). If you roll a 4 and a 5, thenyou can move one pip each from points D and E. You don'thave to bear off; if you wish, you can use your roll to movepieces normally. In case you cannot bear off a pip becausea point is empty, then you can move a pip from the nextlower point. Remember, if you should be "hit" and lose apip to the bar, then you cannot bear off any more pips untilyou retrieve that pip from the bar and move it back aroundto your "home table". The player who first bears off all ofhis pips wins the game. This implementation of backgammon makes it very easy to playthe game. It is fully prompting, with a few "beeps" and"boops" to prompt you for your moves. While the computerthinks, a subtle clicking sound lets you know something isgoing on. If you find the noises offensive, you can pressF1 to toggle the sound off and on. The computer tries toanticipate your moves. For example, when you roll doublesor when you have already taken one of your two moves, thecomputer does not stop to ask you "how many points you wantto move" since the answer is obvious. In other obvioussituations, the computer will supply the answerautomatically. The only non-obvious situation is bearingoff; when you wish to bear off, simply press ENTER whenprompted for HOW MANY? That's all you need to know. Goodluck and enjoy backgammon!