programmable read only memory eeprom the input signals from main shaft encoder 40 are used by each indexer 41 or 42 to output a pulse stream to the respective servo drive 43 44 which control operation of the yarn and cloth feed servo motors m3 m4 each pulse from the indexers 41 42 is translated into steps on servo drives 43 44 for the yarn feed rolls 21 there are between 0 5 5 steps on the servo drive 43 for each pulse from the encoder 40 the computer 50 is also used to set up interrups and an interrupt occurs for every complete revolution of the cloth roll 27 the cloth roll 27 is a spike roll which might typically have a circumference of 12 566 inches each interrupt results in the incrementing of a counter representing the linear length of carpet produced when the computer controlled tufting machine 10 is powered up the resident software program defining the operator interface 51 goes through a system initialization cycle wherein the graphics mode is set the indexers 41 42 for the yarn feed and cloth feed are reset the touch screen 70 is initialized interrupts are enabled timers are initialized and the tufting machine 10 is 34 locked out 34 to prevent inadvertent operation after the system is initialized the first menu is displayed each menu requires operator interaction before another menu can be displayed as indicated in fig6 the machine operator is given the choice on touch screen 53 of setting style information block 53a selecting the maintenance.