ello there tnx justin, you helped very much... I collected many informations and now I already ordered core with PIC18F452 (including bootloader) and SID module for 6581 from Mike's Midishop, cause I am from Slovenia (Europe) and he accept money payments... now I have two questions again: - is possible to build a digital audio output in to midibox sid? I prefer on digital audio outputs since I have audio interface with only digital I/O audio interface (RME HDSP 9652) in my computer - my sound chip 6581 from c64 has a mark R3 beside and I don't know what it means, is it important? that's all for now, tnx and have phun