Subject: comprobe and a GoldeGateII attached ISA bus
To: None <>
From: Niklas Hallqvist <>
List: amiga-dev
Date: 08/21/1994 20:48:11
I'm porting the i386/isa/com.c driver t owork with a GoldenGateII
(which is a card for Amigas wich connect the Zorro2 bus with the
ISA bus also found in some amigas).  In the comprobe1 routine,
there is a inb() call reading the com_iir ioport.  Evidently, if
there isn't a com port there, that inb() should return non-zero.
My problem is that such uses of inb() to non-existant ports returns
just that, ZERO.  Now, I know nothing of the 8250/16450/16550 ICs
at all.  Considering I can't change my HW: are there any other
good ways to probe for these UARTs?  For the moment I just check
if I get a non-zero value and if so I say it's a COM port there.
I get 0x01 returned from the inb() call if there *is* a COM port
there and 0x00 otherwise.

General question: Does the ISA spec (if there is such a spec)
require the data lines to float to ones if there isn't HW available
responding to these inb requests?


Niklas Hallqvist	Phone: +46-(0)31-40 75 00
Applitron Datasystem	Fax:   +46-(0)31-83 39 50
Molndalsvagen 95	Email:
S-412 63  GOTEBORG, Sweden