Os/2 Version 2.X And Os/2 Warp - Brainboxes RS422 Manual

Software Configuration

OS/2 Version 2.x and OS/2 Warp.

OS/2 provides built in support for up to four serial ports.
OS/2 assumes that COM1 is on IRQ4 and that COM2 is on IRQ3.
To use COM3 and COM4 ports on AT bus machines it is necessary
to include parameters on the DEVICE=COM.SYS statement in the
CONFIG.SYS file. That is:-
DEVICE=COM.SYS (N,XXX,I)
where N is the COM port number ( 3 or 4)
XXX is the I/O port address (3E8, 2E8, etc.)
I is the IRQ (interrupt) level (from 1 to 15 )
For COM3 using IRQ10 the CONFIG.SYS file entry should be:-
DEVICE=COM.SYS (3,3E8,10)
For COM4 using IRQ11 the CONFIG.SYS file entry should be:-
DEVICE=COM.SYS (4,2E8,11)
For both COM3 using IRQ10 and COM4 using IRQ11 the
CONFIG.SYS file entry should be:-
DEVICE=COM.SYS (3,3E8,10) (4,2E8,11)
Ensure that 1 space character is between the closing bracket
,10) of COM3 setting and the opening bracket (4, of COM4
setting.
When using OS/2 note that these settings DO NOT get
passed on to the WINOS/2 control panel but also have to be set as
for Windows 3.1, see above. If the standard COM3 or COM4
addresses are not used, and a mouse is on COM1/2, in DOS VDMs
the ADDRCOM3/4 programs may report COM port addresses in a
different order to that expected. However the MODE command
etc. correctly accesses the right port in both DOS VDM and OS/2
sessions.
Please Note:
As with Windows 3.1, OS/2 STRONGLY recommends, and
automatically detects, the use of 16550 FIFO chips on serial ports.
Chapter 4 Page 54
AT & OPTO DUAL RS422/485