 There was even a way of implementing "interrupts" in the BASIC program if two sprites collided, if a sprite collided with other graphics and/or text on the screen, or if an attached light pen was activated.A COLINT command set up the interrupt, pointing to the beginning BASIC line number of the "interrupt handler", which had to end in a RETURN statement (part of standard, unexpanded BASIC) in order to transfer control back to the interrupted, "mainline" part of the program.Playing a sequence of musical notes was hooked onto the standard BASIC "PRINT" command by the use of a special "control character", much like the cursor control, color changes and other control characters.