It is a quad 2 input NAND gate and in the 74 TTL series will be 7400 (7403 is open collector). In CMOS series 4012 Colin -- cdb, bodgy1@optusnet.com.au on 17/11/2002 -- http://www.piclist.com hint: To leave the PICList mailto:piclist-unsubscribe-request@mitvma.mit.edu