var myGifCnt, myGifTbl, mySrcTbl, i;
myGifCnt = 14;
myGifTbl = new Array("Img/100.gif", "Img/101.gif", "Img/102.gif", "Img/103.gif", "Img/104.gif", "Img/105.gif", "Img/106.gif", "Img/1001.gif", "Img/1011.gif", "Img/1021.gif", "Img/1031.gif", "Img/1041.gif", "Img/1051.gif", "Img/1061.gif");
mySrcTbl = new Array(myGifCnt);
for (i = 0; i < myGifCnt; i++) {
    mySrcTbl[i] = new Image();
    mySrcTbl[i].src = myGifTbl[i];
}

function myChange(myBtnNo, myTblNo) {
    document.images["myBtn" + myBtnNo].src = mySrcTbl[myTblNo].src;
}