ISA I/O port programming question...

Robert Erlich (erlichr@interlog.com)
Sun, 12 Jan 1997 20:27:08 -0500 (EST)


Hello all;

I wonder if there are any of you in kernel land that might be able to help
me with this, as it is less a kernel question (although it does involve
creating a driver) and more a hardware question.

I am adapting a servo motor controller board to the ISA buss. (it was
originally designed for the New Micros NMIS microcontroller family) I
would like to place it in an I/O space far away from my other periphs.;
ie. 65535 >= port >=1024.

What is the magic of I/O ports below 0x3FF on the ISA buss? Some texts I
have read state that only the first 10 bits of the I/O address are decoded
onto the ISA buss. Is this true? Do addresses that
are higher wrap around? Are the address lines available to create
hardware that decodes to a >=1024 I/O address? If not, what happens if I
outb(0x400, 0xXX)? All these questions....

Thanks in advance

Robert
...