MSM82C51A-2RS USART ( Universal Synchronous Asynchronous Reciever Transmitter) In a 28 pin DIP package by OKI Semiconductor. This is the hgigher speed version of the popular MSM82C51A. Download OKI MSM82C51A-2 datasheet: Status: NOS (New Old Stock) Also known M82C51A-2 due to shortened top side markings. RoHS Compliant: no