Communication Software

File Name:      MDMCOM1.SYS
Title:  Laptop problems with Windows-based communications programs not able to talk to PCMCIA modem when modem is set to COM1.
PRODUCTS AFFECTED:  Contura Aero, LTE Elite, Contura 400
OPERATING SYSTEM:  MS-DOS 5.0 or greater

DESCRIPTION:  MDMCOM1.SYS (dated 9-14-94) allows Windows-based apps to communicate with a PCMCIA modem that is assigned to COM1. Normally PCMCIA modems are set for COM2 (for some sound technical reasons) but some customers insist that the modem be set for COM1.  Setting the PCMCIA modem to COM1 may cause Windows apps to be completely unable to talk to the modem - MDMCOM1.SYS allows normal operation for those apps.

Date: 07-12-94

SYSTEM REQUIREMENTS: a COMPAQ portable computer with PCMCIA slot(s) modem or serial port with 16550 UART emulation MS-DOS Version 5 or greater MS Windows 3.1

SSCOMM.DRV (dated 7-12-94) has been modified to help Windows programs avoid file transfer failures and dropped characters when using 14400 baud PCMCIA modems on COMPAQ laptops. 

WHO SHOULD USE: Anyone using a COMPAQ laptop or subnotebook (especially AERO) may have problems with Windows-based communications programs (i.e.Terminal, Procomm for Windows) and 14400 baud modems when using baud rates of 19200 and higher in the communication program.  These problems may include file transfers that abort mysteriously (or fail to start at all) and missing characters in screenfuls of received data. SSCOMM.DRV (dated 7-12-94) makes optimal use of the FIFO buffers present in those modems with 16550 UART emulation - this keeps the modem from losing incoming data even if the system cpu is very busy and somewhat slow to respond to the modem.  ONLY THOSE MODEMS (and serial ports) WITH 16550 EMULATION WILL BENEFIT. The following products have 16550 UART emulation: COMPAQ SPEEDPAQ 144/P COMPAQ AERO and ELITE system board serial ports


File Name:    MASKIRQ.EXE
Title:   Fixes DOS Communications Programs on Laptops
CATEGORY:  Drivers / Miscellaneous
PRODUCTS AFFECTED:  Elite, Aero and Contura 400 laptops
OPERATING SYSTEM:  MS-DOS 5.0 or greater
DESCRIPTION:  Some DOS communication programs unable to load or unable to talk to the serial port/modem on the laptop products affected.  

DOS does not provide interrupt driven access to serial ports, so each DOS program that accesses a serial port/modem has its own interrupt handler code. Some of these programs will refuse to load or talk to the serial port if they think that the port is already in use by another program.  

One of the ways that a program can detect that another program is using a serial port is by examining whether or not the Interrupt Request (IRQ) line is enabled (unmasked) for that serial port.

The serial port interrupts on the ELITE, AERO and Contura 400 laptops are left unmasked after POST to solve problems with some software products.

Unfortunately, other software products seem to be adversely affected by the fix for the first group. 

MASKIRQ.EXE allows the user to control the mask/unmask status for IRQ lines 3,4,5 and 7 to suit the programs in use on any given machine.   MASKIRQ may be run from a DOS batch file or as a line in CONFIG.SYS.

NOTE:  If a DOS program is having trouble in a Windows DOS box, it may be best to change the mask/unmask status BEFORE STARTING Windows.

is a DOS utility to allow control of the FIFOs in a 16550-based serial port. COMFIFO may help Contura Aero users with DOS communications programs that are crashing or not working.

FIX for Delrina DosFax
Allows DOSFAX by Delrina to function properly in Compaq PCMCIA
computers when going into standby or hot-plugging/unplugging the