Hello,
After about 50 hours, I can't get Knoppix (HD-installed, Debian-type) to access my modem.
The modem is a 3com/USR 5610 PCI hardware modem (NOT a winmodem) with onboard serial port at d000, IRQ 19.
(REVISED) After about 50 more hours,
In /var/lib/setserial/autoserial.conf :
/dev/ttyS1 uart 16550A port 0xd000 auto_irq baud_base 115200 spd_normal
This fixed the problem. Anyone with a USR 5610 should see this excellent post:
http://lists.debian.org/debian-user/.../msg01462.html
Thanks & 73,

Atari 800 Home Computer System 800 Untested
$95.00
Vintage Atari 410 Program Recorder CIB Open Box Appears Unused 400 800
$194.99
DEFECTIVE Atari 810 Vintage Computer Disk Drive powers on Unit Only Boo G3D
$55.24
ATARI 800 XL 8-Bit Computer w/ Power Supply
$169.00
PERCOM RFD40-S1 Floppy Disk Drive for Atari 400/800/XL Computer UNTESTED
$100.00
Fujinet 1.7.1 Atari 400 800 800XL 130XE 65XE XEGS Assembled, Tested, Working
$99.99
Atari Jumbo Jet Pilot Vintage Floppy Disk Software Lot w/ 2 Disks
$29.99
Atari ST Boot Disk SH CA026391-053 Rev 8 TESTED 1985 Made Japan Original
$44.95
Vintage Atari 800 Computer + 1050 Disk Drive Manuals Games Software Cables Power
$349.00
Atari 1040ST Computer System SM124 Monitor Megafile 60 SLMC804 Bundle W/ Boxes
$849.00