Hi Oliver,

at first I used never the FIFO, only the receive interrupt.
But this crashes on my notebook.
So I manipulate also the FIFO control register.
And only whenever the DMA mode bit (bit 3) was cleared, it works fine.

Also it make no sense to enable the FIFO, if the interrupt was not used.
Since a 16 byte FIFO is to little.
My receive interrupt handler establish a 2kB FIFO in software.
This was enough for my application.
So the 16 byte hardware FIFO was only good to reduce the CPU usage, but never to avoid data loss.

On leaving my DOS program, I disable the UART interrupt, since reenabling the previous interrupt handler crashes also on the notebook.

Now I run the logging program in a DOS-box, format a disk in another DOS-box, and write this message in the foreground and all this works fine.

This is my main Windows usage: a DOS-boxes manager


Peter