INS8251

~National . ~ Semiconductor AUGUST 1978 Pub. No. 426305429-001 A INS8251 Programmable Communication Interface ." c8 General Description Features ii1 The INSB251 is a programmable Universal Synchronous/ Synchronous and Asynchronous Full Duplex 3 Asynchronous Receiver/Transmitter (USART) chip contained in a standard 2B-pin dual-in-line package_ The Operations Synchronous Mode Capabilities 3 Q) chip, which is fabricated using N-channel silicon gate technology, functions as a serial data input/output interface in National Semiconductor's NBOBO micro- - Selectable 5- to B-Bit Characters - Internal or External Character Synchronization - Automatic Sync Insertion C" CD computer family. The functional configuration of the INSB251 is programmed by the system software for Asynchronous Mode Capabilities - Selectable 5- to B-Bit Characters ~ maximum flexibility, thereby allowing the system to receive and transmit virtu .-'Iy any serial data communica. tion signal presently in use (including IBM Bisync). The INSB251 can be programmed to receive and transmit either synchrpnous or asynchronous serial data_ The INSB251 performs serial-to-parallel conversion on data characters received from an input/output device or a MODEM, and parallel-to-serial conversion on data char~cters received from the CPU. The CPU can read the - 3 Selectable Clock Rates (1 x, 16x or 64x the Baud Rate) - Line Break Detection and Generation - 1-, 1%-, or 2-Stop Bit Detection and Generation...