If you consider the issues, CardBus is actually a more difficult
environment. The driver must contend with switching between two
incompatible signaling schemes (PCMCIA is ISA-like), reading an overly
complicated CIS, setting the voltages and timings according to what was read
from the CIS, and rapid insert/eject cycles(*).
Both hot-swap PCI and CardBus require multiple logical bus bridges that can
disconnect the signal leads and turn off power to just one slot, so don't
try hot-plugging cards on your standard desktop machine!
* IBM's hot-swap implementation sends an "eject" signal when you pivot the
PCI card hold-down. There is plenty of time before the card is removed. In
contrast, CardBus drivers must deal with the card going away without
warning, or a barely-inserted card that is activated many times a second.
Donald Becker Scyld Computing Corporation
becker@tidalwave.net
240-463-0035 (voice) Columbia MD
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