: Hint: Timing with interrupts is important, especially if more than one interrupts run. If the interval of a subroutine driven by an interrupt is too long than the processor can never get back to deal the main program again. Work out timing by measuring the subroutine or by trial and error.
: There are system internal interrupts (highest level) which cannot be influenced by BASIC interrupts (e.g. keyboard scan <> BREAK key.): On the The next level of sytem internal interrupts can CAN be influenced by BASIC interrupts. E.g. For example the sound queue which will be created by "ON SQ <chanel> GOSUB <line>". Those sound interrupts have a an independent time tricker but their priority is parallel to the second priority times of BASICBASICs interrupts. Therefore interrupts with timer 3 could "interrupt" them.
==== <code>FILL i</code> ====