On Sun, Jan 12, 2003 at 12:25:16PM -0800, Ben Barrett wrote: > As a follow-up, does anyone have a concise and/or recent link on > ISA-PCMCIA bridge support in Linux? I found a couple references, but > nothing that was really helpful in instructing me to us one -- I have > one of the old Lucent ones iirc, and have never been able to use my > pcmcia 802.11b card with a desktop system. I since have it plugged into > my access point, and the ISA bridge sits useless... someone please tell > me it is not = )
PCMCIA is an ISA-based standard. Actually as it happens, PCMCIA is more
or less an IDE interface with some interesting tweaks. The devices on a
PCMCIA controller are typically integrated versions of what you'd plug in
to an ISA bus. ie, they talk over ports, use interrupts, and use DMA
channels. This reduced the development costs of PCMCIA cards.
CardBus is an extension to the PCMCIA spec which allows for a bit of nice
multiplexing. The details I do not know for certain, but ISTR CardBus has
the equivalent of PCI channels, again allowing for people making them to
basically lift the logic from existing PCI devices and use it almost
wholesale in the CardBus devices.
At some point, laptop makers decided PCMCIA sounded stupid and started
calling the things "PC Cards". This never caught on, but never really
went away, and many geeks still call what's on their laptops PCMCIA slots.
If your laptop was made in the past five years though, almost certainly
they are actually CardBus slots. Unless you're dealing with a PowerBook
or iBook, the CardBus controller still provides the equivalent of an ISA
bridge to talk to old PCMCIA cards. This isn't really a slowdown, unless
compared to using a CardBus device, which runs faster than 8MHz.
If you cannot use the PCMCIA device on a CardBus controller and you're not
running a Mac, I'd be surprised.
> PS - Yes, it is ISA, not PCI. Slows down the rest of the bus in a mixed
> PCI/ISA machine afaik.
Every single PCI machine has an ISA bridge. Your keyboard and floppy
drives kinda depend on the ISA bus, after all. Most people depend at
least on these devices actually working at least some of the time. The
ISA side of an ISA-PCI bridge is only 8MHz, but this does not impact the
speed of the PCI bus.
CardBus should not be any different.
--
Joseph Carter <[EMAIL PROTECTED]> You want fries with that?
<lilo> it's weird, when you go on a safari to Africa to catch a lion, you
find it alive and it charges, and then you kill it
<lilo> when you go on a safari to South Bay to find a Palm Vx, you find
it dead and take it home and it charges after it arrives :)
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