by I have a multi I/O card which has 4 serial, 3 parallel, and 1 game
port. For each of the serial and parallel ports there is a jumper to
set the IRQ to one of 3,4,5,7,9,10,11,12,15. For each serial port
there is a additional jumper to the port address to one of {2,3}{e,f}8
while the parallel ports can be set to 278, 378 or 3bc.
The card has two 16552 and one 86c451 chip.
The Linux kernel recognizes 4 serial ports at the 4 different
addresses as set by the jumpers.
My questions is, wether this card is multiport card as described in
the Serial-HOWTO, i.e. which can share one IRQ among several serial
ports.
I have set the jumpers for ttyS0 and ttyS2 to IRQ 4, the other two to
IRQ 3.
When I start X, the mouse connected to ttyS0 works correctly. But
when I then type
cat /dev/ttyS2 >foo
the mouse movements aren't seen by the X server anymore. It seems
when an IRQ 4 occurs the interrupt routine tries to read from ttyS2
only, as long as it is opened. If I kill the cat, the mosue operates
again.
The guy from which I bought this card has used it with the same jumper
setting, i.e. two serial ports per IRQ, but on an OS other than Linux.
I don't know I he has used two of those ports simulanously.
Can I use two serial ports on this card simulanously using the same
interrupt?
urs