Do you have "flags 1" on the com? devices which are on the AST card?
This causes the com driver to *not* assert MCR_IENABLE, which is
necessary in order for the devices to interrupt properly in enhanced
mode.

I made the mistake once of off the flags and saw failures similar to
what you were seeing (I think caused by interrupt conflicts..)

Perhaps the ast driver should force `flags 1' for it's slaves...

Here's the relevant section out of my config file..

device		com0	at isa? port "IO_COM1" irq 4 
device		com1	at isa? port "IO_COM2" irq 3 

master		ast0	at isa? port 0x1a0 irq 5
device		com2	at ast0 slave 0 flags 1
device		com3	at ast0 slave 1 flags 1
device		com4	at ast0 slave 2 flags 1
device		com5	at ast0 slave 3 flags 1

					- Bill

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