How do I use interrupts in SBasic?
When the 68hc11 receives an interrupt, the MCU saves the current state of the registers, fetchs the contents of the appropriate interrupt vector, and jumps to that address. So the key element of handling interrupts in SBasic is to ensure that the address of your interrupt routine gets stored in the correct vector address. The following example uses the real-time interrupt (RTI), as it may be the most commonly used. Here is a typical RTI interrupt service routine (ISR): interrupt $fff0 ; vector for RTI if wait <> 0 ; if counter not yet 0… wait = wait – 1 ; decrement it endif pokeb tflg2, %01000000 ; rearm RTI end ; end of the ISR You can put this routine anywhere you want in your SBasic source file, but it makes the most sense to put it after your variable declarations but before your MAIN label. The first line in this routine tells SBasic to write the address of this code block to the vector address $fff0, which happens to be the vector address for the RTI interrupt. The POKEB statem
