Here's the old assembly code which works perfectly: LOCAL MODE LOCAL FN YieldToAnyThread '--------------------------------------- ` CLR.W -(SP) ` DC.W $42A7,$303C,$0205,$ABF2 ` MOVE.W (SP)+,D0 ` EXT.L D0 END FN = REGISTER(D0) 'OSErr Here's the new TOOLBOX code I wrote: TOOLBOX FN YieldToAnyThread = WORD `0x42A7,0x303C,0x0205,0xABF2 Is that correct? It seems to compile and run (though further testing is needed) when I compile cpu68k but not when I compile cpuPPC. cpuPPC crashes into macsbug. Is there a PPC 'gotcha' with these toolbox calls that I don't know about? --Steve _____________________________ Steven J. Stratford, InterNetyx.com Supercharge your website! www.internetyx.com 920-206-9197 _____________________________