This part is a kind of semiconductor called NS16550A.

Function of this product has UART Design and Application Considerations.

Manufacturers : National Semiconductor

Image and pinout :

Some of the text within the PDF file :

The NS16550A UART Design and Application Considerations The NS16550A UART Design and Application Considerations BACKGROUND UARTs like other system components have evolved for many years to become faster more integrated and less expensive The rise in popularity of the personal computer with its focus and competition primarily centered on an architecture introduced by IBM has driven both UART performance and software compatibility issues As transmission rates have increased the amount of time the CPU has for other tasks while handling an active serial channel has been sharply reduced One byte of data received at 1200 baud (8 3 ms) is received in th the time at 19 2 kbaud (520 ms) Software compatibility among the PC-based UARTs is critical due to the thousands of existin [ ... ]

NS16550A PDF Datasheet Download