MM74HC688N 8-bit equality comparator by National Semiconductor. Package: 20-DIP Download National Semiconductor MM74HC688N .pdf datasheet: Dual topside markings : MM74HC688N / MC74HC688N Status: NOS (New Old Stock) selling on auction sites for £4.60 each ! (2020) our price a sensible £1.20 Individually tested Components: YES RoHS compliant: tbc