Based on my understanding, a UART chip is a chip that exists on a serial card, and it is responsible for the actual sending and receiving of data over the serial port.

I want to see what a UART chip actually looks like on a serial card.

The following is a PCI serial card:

enter image description here

Is the chip circled in yellow the UART chip?

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    It's more than just a UART. It's also includes PCI bus logic and based on the unpopulated connectors it probably also includes a second UART and a parallel interface. You can see here what a plain UART chip looks like: en.wikipedia.org/wiki/8250_UART – Ross Ridge Oct 24 '17 at 3:42
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    Yah, the chip looks like an MCS9835CV-BA PCI to Dual Serial and Single Parallel Controller: asix.com.tw/products.php?op=pItemdetail&PItemID=127;74;111 – Ross Ridge Oct 24 '17 at 3:49
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    Indeed; this is a multi-function chip that provides several integrated features, one of which is behaving as a UART. If, as your question suggests, what you want is to see what a UART would look like, you would generally expect it to have a lot fewer pins than this chip has, because the job it's doing is simpler. The canonical implementation of a UART these days is the 16550. It's a more modern version of the UART used in the original IBM PC, the 8250. – Jules Oct 24 '17 at 5:10
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    Guys these should probably be answers, not comments! – Wilson Oct 24 '17 at 7:35
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    This is off-topic. With a specific board it might be on-topic but I'm not sure whether that would be an interesting question. – wizzwizz4 Oct 25 '17 at 8:30

That chip is an ASIX MCS9820, as seen on a (current) StarTech 1 Port PCI RS232 Serial Adapter Card with 16550 UART. While it contains UART functions, the chip itself is a PCI→Serial bridge.

The chip emulates a National Semiconductor 16550 UART, itself an improved version of the NS 8250 found in the IBM PC. 8-bit computers often had a Motorola 6850 or MOS 6551 Asynchronous Communications Interface Adapter (ACIA). These would be more in line with this SE's remit.

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