Why is bus_set_resource() rarely used? Docs for ISA cards

[Alexander Farber]

Hi,

I'm trying to learn how the i4b ISA drivers are 
programmed by reading the "Arch Handbook" and looking 
at i4b/capi/iavc/iavc_isa.c on my FreeBSD 4-stable PC
and wonder why doesn't iavc (and most other ISDN cards)
use bus_set_resource()? I only see bus_alloc_resource()
being called for SYS_RES_IOPORT and _IRQ in iavc_isa.c

Also I have the following ISA cards:

	AVM ISA v3.0
	USR Sportster
	Teles 16.3
	Siemens smth.

Where did the people writing drivers for those cards
get the information on how to reset those cards, to
which ports to write what, etc.? Could someone please
point me to the docs? Thanks

Regards
Alex

[1] http://www.freebsd.org/doc/en_US.ISO8859-1/books/arch-handbook/isa-driver-resources.html