Using PCI Multiport Cards Under MSDOS
Most new motherboards no longer include
ISA slots. As such if you once used ISA multiport or single port serial
cards with custom software you developed you may think that you are at
an impasse. If that is the case, do not despair.
Most non-intelligent multiport cards
behave virtually the same as the ISA multiport cards. There is an
interrupt request line (IRQ) for the card as well as the base address
for the UARTs on the card. Unlike ISA cards, there are generally no
jumpers/switches to determine or to set the IRQs and addresses. The PCI
architecture allows for auto configuring of PCI cards.
In order to determine the address and IRQ
of the PCI serial multiport card, your application must read what is
known as the PCI configuration space of the card. While not difficult it
can be a bit error prone. We have a utility that can be freely download
named
PCIFind.exe.
The utility requires both the vendor ID and
device ID of the serial multiport card whose address you want. Some
motherboards will actually display these values at boot time for each
PCI card in the computer. Alternatively, you can call the manufacturer to get these two values. Once you are able to determine the address and IRQ of the
multiport card, you can program your application as you would any other
multiport ISA card.
We have several tools that support PCI
multiport cards. Specifically COMM-DRV/Dos
and COMM-DRV/Lib provide drivers
and libraries to simplify development. We also have a myriad of PCI
multiport serial cards of RS232, RS422,
RS485 flavors.
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