Category : Communication (modem) tools and utilities
Archive   : NMODM215.ZIP
Filename : TROUBLE.DOC

I have NMODEM running on FALCON, FeatherNet and WildCat! BBS systems! It
has been found to work on AT/XT class machines under MS-DOS 3.3/4.01,
OS/2, DR-DOS 5.0, PC-MOS 4.1, Concurrent DOS-XM 6.2, and Concurrent DOS-386
3.0. My machines all run PHOENIX 2.52 BIOS for XT class, the AT-CLONE has
an early (1987) PHOENIX BIOS licensed to Tandy (Same as PHOENIX 3.06), and
my 386-25 has AWARD 3.11 BIOS. NMODEM has been tested with TELIX 3.11/3.15,
QMODEM 4.2 and GT1550. All of my modems are EVEREX EV-940 models with
ROCKWELL Chip set.

If you experience problems with NMODEM.EXE try NMTERM.EXE! If the
terminal version works then you must suspect the way the Comm or
BBS program you are using does a shell to DOS as whats causing NMODEM
to malfunction.

Malfunctions could be caused by one or more of the following:

1. TSR interference.

2. Multiple Comm ports at same address and/or interrupt.
- This problem can be a real killer since most diganostic
programs will NOT even detect this problem. Some programs will
function in this environment and others won't. I know for
a fact that NMODEM has worked in a variation of this problem
on THE COMM CENTER, but DOS, Hardware, BIOS,etc all contribute
to troubles in this area. I suggest going to COM3: if your
your modem will support COM3:. Most problems involve COM1 &
COM2:. I finally had to switch THE COMM CENTER to eliminate
interference from a buggy EMS card!

3. Buggy UART in port.(many buggy UARTS are out there!!)

4. Bad UART interface built into NMODEM.

5. Incorrect switch settings on modem and/or incorrect init string
for the modem.

6. Passing wrong port # to NMODEM.

7. Passing wrong data to NMODEM for port# or file.

8. Early versions of DOS 4.01 had a major bug which can cause very
strange inconsistent operational problems. All 1988 versions were
bad! Early 1989 versions were bad! After April/May 1989 a patch
was issued for MS-DOS 4.01 which seems to finally cleaned it up.
IBM has released a replacement for PC-DOS 4.01 which may or may
NOT correct the problem. The MS-DOS 4.01 patch program is on
PYSMATIC (415)-969-4159 for download.

9. NMODEM tries to be very straight forward and NOT use any tricks
or undocumented features of DOS. Video cards and some ROM BIOS
versions have undocumented side effects and/or operational defects
which can cause unsuspected problems. If your ROM BIOS is NOT
PHOENIX, AWARD, AMI or IBM then it could be causing problems. Early
versions of ALL BIOSs have bugs which were resolved in newer
upgrades. If your BIOS is an earlier version it could have some
side effects.

10. A problem floppy controller as reported by one of my local callers.

The multitude of variations of hardware, software, operating systems
and BIOS types in IBM "compatable" machines makes it impossible to
test for everything. I have made an effort to establish some basis
to believe it will function, but cannot guarantee it will work!

NOTE: "Hayes Compatible" does NOT mean the modem is 100% to the
"standard"!! The EVEREX modems are NOT 100% Hayes compatable
"thank heavens", however they do respond basically as a
"HAYES" would with many powerful extensions to the features
and command set. All modems are "compatable" in varying ways
and thus will interact differently with any program.