Apple Macintosh LC 630 DOS - Manual (Page 74)

Configuring the PC serial ports
Your DOS-compatible Macintosh supports two serial ports, COM1 and
COM2. You can map these ports to an unused Macintosh printer port or
modem port, to a text file for later processing, or to a setting of None.
m To assign a Macintosh serial port to a COM port, make a selection in the COM port’s
pop-up menu.
When you map a port to a text file, a dialog box appears that you use to
specify a name and location for the file. Macintosh serial ports already in use
appear dimmed in the menu. (The printer port may be in use by AppleTalk,
which may be used for a network or LaserWriter connection; the modem port
may be in use by communications or fax software.) Changes to these
selections take place immediately.
Assigned ports may not be available to the Mac OS: Mac OS programs may no
longer be able to access ports that you’ve assigned to DOS. Allocate these
ports only when they’re needed, and deallocate them when they’re no longer
required by your DOS programs. (You won’t have to restart the computer to
have the changes take effect.)
The maximum baud rate supported by the DOS-compatible Macintosh when
a COM port is mapped to a Macintosh serial port is 19,200. However, when
the MODE command is issued in DOS and the serial port is set at 19,200
baud, the incorrect message “Function not supported on this computer” is
displayed. This occurs because DOS is looking for specific hardware (a PC
UART) that is not emulated by the DOS-compatible Macintosh. The
Macintosh actually does support 19,200 baud, and can be set by a number of
communication application programs.
63 Configuring the PC Environment