Copy these drivers into your OS/2 installation.

COPY COM177.SYS x:\OS2
COPY VCOM177.SYS x:\OS2\MDOS

Edit your CONFIG.SYS file to change the x:\OS2\COM.SYS and
x:\OS2\MDOS\VCOM.SYS respectively, where x: is the drive where the
OS/2 system files reside.  example:

DEVICE=x:\OS2\COM177.SYS
DEVICE=x:\OS2\MDOS\VCOM177.SYS

Next, the following parameters must be added to the COM driver calling
lines in your CONFIG.SYS if you wish to use COM 3 and/or 4, or COM 1 
and/or 2 not installed on the 'default' interrupts:

DEVICE=x:\OS2\COM177.SYS (n,xxx,i) (n,xxx,i)
DEVICE=x:\OS2\MDOS\VCOM177.SYS (n,xxx,i) (n,xxx,i)

X is the drive that OS/2 is installed
n is the COM port number (1, 2, 3, or 4)
xxx is the COM port address (3e8, 2e8, 3320, etc.)
i is the IRQ level (from 1 to 15)


An example to install COM4:

DEVICE=C:\OS2\COM177.SYS (4,2E8,9)
DEVICE=C:\OS2\VCOM177.SYS (4,2E8,9)

An example to install COM2, COM3, and COM4 (COM1 is used for the mouse): 

DEVICE=C:\OS2\COM177.SYS (2,2F8,3) (3,3E8,5) (4,2E8,9)
DEVICE=C:\OS2\MDOS\VCOM177.SYS (2,2F8,3) (3,3E8,5) (4,2E8,9)

These restrictions to apply COM 3 & 4 support in AT bus machines:

COM 3 or COM 4 may have the same IRQ level as COM 1 or COM 2.  However, when
the COM port is open, the other COM ports which use the same IRQ level
cannot be opened.  With OS/2 applications, the open call for the COM port fails.
With DOS applications, they often go into an infinite loop and hang the 
VDM session since the open to the COM port cannot be done.  It is
strongly recommended to use different IRQ levels for different COM port.

The port address cannot be shared.  If a port address is shared by two or
more COM port, it will create unpredictable outcome.

Although we may put any preferred values to install COM 3 and/or 4,
the ports or COM177.SYS may not be able to perform as they should if
the values are different from the ones specified by the COM 3 and
COM 4 adapter cards.  For example, if a FAX/MODEM card can be
configured as COM 4, but the documentation indicates that the IRQ will
be 3 when COM 4 is chosen.  If COM177.SYS is installed for COM 2 which
uses IRQ 3, there will be a conflict in IRQ level.  COM177.SYS will make
both COM 2 and COM 4 available, but both ports cannot be opened at the
same time.  If the user would like to use COM4, it is recommended to
disable COM2 or to remove the COM2 adapter card.

These drivers do not 'steal' the NS16550 UART Chip.