Nice! I would guess the DMA used now could be attempts at using the serial comms. 8237 DMA channels are used for serial communications, expansion devices, graphics, and disks (on this system floppy drives use a DMA channel on the 80186). DMA support for the i8274/uPD7201 is not implemented.
I would guess the DMA used now could be attempts at using the serial comms. 8237 DMA channels are used for serial communications, expansion devices, graphics, and disks (on this system floppy drives use a DMA channel on the 80186).
