What is the type of the UART chip used by Virtual Box?

Based on my understanding, a UART chip is used to control the serial port (the programmer manipulates the UART registers in order to access the serial port). There are many types of UART chips (for example: UART 16550, 8250 UART, etc.).

I am trying to write a small program in Assembly (on Virtual Box) that accesses the serial port directly (without using a serial port driver or BIOS). But I need to knows what is the type of the UART chip used by Virtual Box, so that I can know what are the registers used by this chip, etc.

I am using Virtual Box 5.1.18.

This is how I enable the serial port in Virtual Box:

Solution 1:

VirtualBox simulates a 16550 UART with the FIFO bug fixed.