[Sorry for the repost. Haven't sent a message to the list in years and didn't realize I needed a topic tag] I have a relay mux that I am actuating using a PIC16F84A, a bunch of 74HC595 serial to parallel shift registers and ULN2803 drivers. Given that I have the SCLK, RCLK, CLR lines all tied in parallel on the 74HC595's, how many 74HC595's can a PIC drive? Is there a table somewhere that shows the current requirements for driving each chip family? TIA Dave -- http://www.piclist.com hint: The list server can filter out subtopics (like ads or off topics) for you. See http://www.piclist.com/#topics