ISA to PCI?

From: Shawn T. Rutledge <ecloud_at_bigfoot.com>
Date: Mon Apr 6 21:54:20 1998

Bruce Lane wrote:
>
> Tim Hotze scribbled...
>
> >the old ISA cards I've collected, I just got an AWE 64, and my scanner and
> >PCMCIA cards are ISA-based. So, is it possible to make a device that will
> >make an ISA card fit into a PCI socket? Is anyone making them?
>
> No one that I know of. In fact, I question that such a device is even
> economically possible to the point that a company would want to try. The
> architecture differences between PCI and ISA are enormous.
>
> The only thing I can think of that -might- stand a chance of working is to
> construct some sort of sub-board that the ISA card would plug into. Said
> sub-board would contain the necessary circuitry to implement an ISA-to-PCI
> bridge.
>
> This means, at bare minimum, dealing with a 220-lead surface-mount PQFP
> chip and its supporting components. That means lots of skill in engineering
> such bridges, to say nothing of having access to schematic capture and PC
> board layout tools that can handle advanced boards...

Sure you would need a bridge chip, but on PCI motherboards the ISA bus is
actually connected to the PCI bus via just such a bridge, rather than directly
to the processor as in AT designs; so evidently it isn't too expensive to do
that. I think it also allows for some flexibility in moving ports, memory
addresses, irq's etc. around, for ISA devices on a PCI bus. That helped make
PnP possible for non-PnP cards (ISA PnP cards also comply to a standard which
allows the system to query which parameters can be changed, and then change
them).

Somebody ought to make an expansion chassis, like the old IBM PC expansion
chassis, that plugs into a card on the PCI bus. That would be handy for
people with lots of cards, more so than individual converter boards, and the
higher retail price would allow a higher profit margin too.

Alternatively, running out of ISA slots is a great excuse to get a second
machine. If you run Linux, it becomes much easier to share resources between
PC's over a network.

-- 
  _______                 KB7PWD _at_ KC7Y.AZ.US.NOAM   ecloud_at_bigfoot.com
 (_  | |_)  Shawn T. Rutledge            http://www.bigfoot.com/~ecloud
 __) | | \_____________________________________________________________
Received on Mon Apr 06 1998 - 21:54:20 BST

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