COM3+ Support

Option I

Use ELODEV 1.7 which has built-in support for COM3 & 4. For example:

	ELODEV 2210,3,9600,10

The last parameter is the IRQ for the COM port. It cannot be a shared 
IRQ. The serial port must be a standard PC UART (16450/550) 
compatible.

Option II

ELODEV also has an open architecture for adding additional COM port 
support. Load ELODEV specifying 0 as the COM port, as in this example:

	ELODEV 2210,0

Then load a special TSR after ELODEV that includes code to handle the 
COM port. An example is available on the DOS Programmer's Toolkit 
diskette, also found in the assembly language file area (ASM.ZIP).

Modify this example, UCOMTSR.ASM, for your interrupt and base port, 
and any other special code you require such as interrupt sharing or a 
non-standard UART. Code is included for operating your COM port at 
IRQ8-15 but is commented out. With UCOMTSR, ELOCALIB, ELODEMO, 
MonitorMouse, etc. will all work with your COM port.

The UCOMTSR code contains procedures to initialize the serial port, 
enable interrupts, and handle the incoming characters. You jump to a 
special location within ELODEV with the character in a register, and 
ELODEV takes it from there. You don't even have to look at the 
character.

Option III

You can also use a PC-Bus touchscreen controller rather than a serial 
controller. The E271-2201 controller is for AccuTouch, and the E281-
4035 is for IntelliTouch. They are Base I/O Port and interrupt (IRQ) 
selectable (2-7) and do not conflict with the COM ports. IRQ2, IRQ5, 
or IRQ7 are typically available (printers do not use interrupts, and 
IRQ2 is remapped to 9).