This part is a kind of semiconductor called NS16550A.

Function of this product has UART.

Manufacturers : National Semiconductor

Image and pinout :

Some of the text within the PDF file :

Accessing the NS16550A UART in the PS 2 Model 50 60 70 and 80 Accessing the NS16550A UART in the PS 2 Model 50 60 70 and 80 INTRODUCTION This paper reviews fundamental concepts of the Micro Channel Architecture and their relation to the NS16550A UART All 4 of the PS 2 personal computers reviewed use the NS16550A for asynchronous serial communication The first part is an overview of the PS 2 system board and Micro Channel Architecture (MCA) in the Models 50 60 70 and 80 personal computers The next part explains the basic configuration and system initialization procedures for the UART that occur after power-up The last part describes the overall interrupt procedure and the advantages of using the on-chip FIFOs of the NS16550A These explanations describe the CPU accesses [ ... ]

NS16550A PDF Datasheet Download