UUCJEFF@ECNCDC.BITNET (04/25/88)
I have just upgraded to a Mega 2, and there is one program which I wrote that previsously ran (although sometime would get bus errors if run from MWC msh) that now gets illegal instruction bombs on the Mega. The program involves an Xbtimer interrupt handler which updates some timers, searches a linked list, and possibly outputs Midiws, and deletes records on the linked list. I follow the model given by the 200 Hz routine in Abacus Internals, plus a previous Antic. I use RTE and clear the ISR register. Are there any unpublished rules about Xbtimer routines? Aside from that, everything else runs except the msh from MWC Version 2.1. Funny thing, the msh from version 1 does run. I'll call up MWC about that one, I want to get version 3.0 anyway, and fortunately their office is in Chicago. Getting back to the Xbtimer routines, the linked list can have insertions done from outside the Xbtimer routine, although my program doesnt yet do this. I protect the code which does the pointer tying by disabling the interrupt. I assume the counter keeps counting and resets whether the routine is called or not. A better way would be to just suspend the timer while keeping all the counters the same, and an even better way would be to have the interrupt pending while that sensitive code is done. Does anyone know how to do this? Thanks for any help, Jeff Beer, UUCJEFF@ECNCDC.BITNET ========================================================================== "Language is a Virus" Laurie Anderson ==========================================================================