FAS Driver on Jameco Boards

[Uwe Doering]

thssdwv at iitmax.IIT.EDU (David William Vrona) writes:

>I have two Jameco serial port boards.  Each can be configured as either COM1
>and COM2 or COM3 and COM4.  They use sharable interrupts, i.e. COM1 and COM3
>share, etc.  I have replaced the UARTs with the 16550AN chips.
>
>I still cannot get FAS 2.06 work with these boards.  Nor can I get the X5 
>update from Interactive to work either.  The problem I have is that COM3 and
>COM4 are dead, COM1 and COM2 work fine.  I have switched the UART's around, and
>all reset the addresses, etc.

I would think that you have been misled by the fact that on your serial cards
there are DIP switches or jumpers that allow you to set two ports to the same
interrupt. This alone doesn't mean that these cards are capable of shared
interrupts. As on every other cheap PC serial card you can only use one
of those ports at the same time if you set them to the same interrupt. In
the DOS environment this isn't much of a problem as DOS isn't multitasking.
Under UNIX all ports have to work at the same time (worst case).

Shareable interrupts require a special logic on the serial card as the
PC or AT i/o bus itself can't handle shared interrupts. One cheap alternative
for you would be one of those AST 4-port clones.

FAS generally runs on nearly every board that maps its ports to separate
i/o addresses. But this requires that you use the proper hardware as FAS
can't compensate hardware limitations.

I think I will write a few words about this subject in the README file
of the next FAS release to prevent people from wasting their time tinkering
with serial cards that simply can't work with FAS due to design
shortcomings.

     Uwe
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