Is it possible to connect my program as a device in qemu?

Question

DOS

For example, in freedos, as I understand it, you can manage different devices. and as I remember from one book, some devices are located at special addresses. and these devices can be communicated with in and out if it is not dma. so here. is it possible to write a program that would respond to incoming data from ports sent to a specific address? for example, in freedos I send a byte to the address mov al, 0x12; out 0x33, al; and the device, for example, starts doing something. well or how it is possible to make that dma was used? I want to know if there is a possibility in the future. perhaps it will be necessary to make an emulator for the device, which will graphically show its work. and the program in freedos will use that device.