in reply to: Re: Where to buy SYM20C15 Hart chips posted by Wolfgang Schmidt on 05 November 2001 at 16:11:22.
It seems that the compatible chip A5191HRT (AMI semiconductor) now has the chip in Germany available.
As for the crystal: the 480.6kHz seems a somewhat unusual frequency, maybe you may derive the clock from your microprocessor. Common available Xtal frequencies:
3.6864MHz (divide in your micro by 2^3=8)
7.3728MHz (divide in your micro by 2^4=16)