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__________________________________________________
T H E
M O D E M
D O C T O R
Version 3.0S /3.0R
Hank Volpe Copyright 1989,1990
108 Broadmoor Drive
Tonawanda NY 14150
__________________________________________________
Section 1.
Forward ...................................................1
Introduction...............................................2
Section 2. Starting MDR....................................3
Section 3. First Time Setup................................4
A. Test Modem/UART......................................5
B. Uart Tests ......................................... 7
C. Return to main menu ................................ 8
Section 4. The Main Menu.................................. 8
4.01 Hot-Key Selection ................................ 9
4.1 Login In Comm ports ..............................10
4.11 What do IRQ's and Comm ports do?..................10
4.12 Port assignments and their meanings...............11
4.13 Testing Defective Ports...........................12
4.2 Regs .............................................13
4.3 Carrier Tests ....................................20
4.31 Modem Driver modules..............................20
4.32 Types of Carrier Tests............................21
4.33 AT Instruction Set tests..........................21
4.34 Uart or Dumb Modem Tests..........................22
4.35 Error Messages....................................23
4.4 Loopback Tests ...................................24
4.41 Loopback test Error Messages......................25
4.5 Manual ...........................................26
4.6 Setup Mode .......................................26
4.7 Exit Program .....................................26
Section 5.Error Messages and Their Meanings...............27
5.1 Log In errors .....................................27
5.2 Carrier Errors ....................................27
5.3 Loopback Errors ...................................29
5.4 Setup Errors ......................................30
Section 6. Special Modes and Information .................32
6.1 Using Modem Drivers ...............................32
6.2 Using the Command Line switch /s ..................34
6.3 Using the Hot-Keys ................................35
6.4 Logging in defective ports.........................36
6.5 What tests cannot do ..............................37
6.6 Quirks with some modems ...........................37
Section 7. Benefits of Registration ......................38
The Modem Doctor Version 3.0 Documentation Page 1
Copyright (c) Hank Volpe 1989,1990
Forward
-------
Welcome to the Modem Doctor. This documentation along with
the program is a good source of information about how Uarts
and Serial Ports work with Modems in your Personal Computer.
There are two versions of the Modem Doctor; The Shareware
version 3.0S and the Registered Version 3.0R. There are some
differences between the two. Both however are full-
functioned diagnostics tools. The differences between the
two are as follows;
Version 3.0S supports COM1 through COM4
Version 3.0R supports COM1 through COM8
Version 3.0S supports speeds to 2400 bps
Version 3.0R supports speeds to 38,400 bps
Version 3.0S does not include Manual Log-in of Comm ports,
the Digital or the Analog Loopback testing supported in
Version 3.0R.
This documentation covers both versions, however the feature
differences above are provided for your reference.
I sincerely hope that you take a good look at the program
and the documentation. The Modem Doctor is about as complete
a diagnostic tool you can find for your Serial Port and
Modem. A complete Program History follows the documentation.
The Modem Doctor Version 2.2 was received very well
nationally and internationally, Version 3.0 now adds more
tests, more user features and more flexibility for you to
use.
Version 3.0S is Shareware and may be freely copied and
distributed. You have a limited license to use Version 3.0S
during a fair-evaluation period. After that time you must
order the Modem Doctor in order to continue using it. Please
be fair and make your decision based on what you see.
Version 3.0R is a Registered Version with additional
features and is licensed to one user only (unless you have a
site license). No copies may be made (except for archival
purposes) and you may not distribute Version 3.0R without
violation of Copyright laws and you license to use the Modem
Doctor.
If you are using the Shareware version and wish to order,
please use the Order form included with this package or see
Section 7, Benefits of registration at the end of this
documentation.
The Modem Doctor Version 3.0 Documentation Page 2
Copyright (c) Hank Volpe 1989,1990
Section 1. Introduction -
-------------------------
The Modem Doctor is a professional diagnostic tool designed
to work with IBM-PC's and compatibles. There are two
versions of the Modem Doctor, the Shareware Version and the
Registered Version. The Registered Version of the Modem
Doctor contains complete diagnostics for 8250 and compatible
UARTS, RS-232 data lines, and Carrier tests. Some of the
many diagnostic features of the Registered Version are;
** Support for COM 1 through COM 8 using system IRQ's 3,4,5
or 7
** Baud Rates from 300 to 38400 bps !! NEW !!
** Support for Courier HST/Dual Standard/V.32 Modems [+]
** Auto-detection of Modems that use &T0 diagnostics
** Auto log-in of COMM ports 1 - 4 to DOS for use by other
programs
** Manual log-in of up to 8 COMM ports for Non-Standard
Hardware,including those with defective Uarts (on manual
selection). !! NEW !!
** On-screen Display of all 8250 /16450/ 16550 Uart
registers
** On-screen Display of Modem S-Registers
** Full Diagnostic tests of UART and RS-232 Channels
including;
-- ALL UART REGISTERS
-- ALL RS-232 Handshaking Signals
-- 8259 Interrupt Controller Mask Registers
-- Digital Loopback UART Tests including Chips
with Tri-stated OUT2 signals
-- Analog Loopback Data Tests
** Full Diagnostic Checks of "AT" Instruction Set
Modems;
-- Carrier Tests on both Originate and Answer
Frequencies
-- Carrier Test interface for "Dumb" Modems or Data
Channels
-- Modem Microprocessor Command Channel Diagnostics
-- Support for High Speed Modems
-- Support for Modems that use the alternate &T0 self
test mode
The Modem Doctor Version 3.0 Documentation Page 3
Copyright (c) Hank Volpe 1989,1990
** Interactive Mode with 4K Communications Buffer for;
-- TTY mode Interactive Communications over serial
port or Modem while on-line
-- Custom Designed Tests...Help Menu Included
-- On-Line "Hot-key" Viewing of 8250 UART Registers
** Hot-Keys for selecting the Baud rate and to Force a
Modem Microprocessor test mode. !! NEW !!
** User Selection of Modem Drivers. Like Printer Drivers,
these software modules add more selections and more test
capability to The Modem Doctor. !! NEW !!
** New Status Bar that continuously displays the Port,
Speed, Microprocessor Status, and Modem Driver
selections. !! NEW !!
** Command Line Mode interface for setting up a modem to an
initialization string contained in a user created file;
!! NEW !!
-- A Small text file contains the port (and optional
address), the speed, and the string to send to the
modem. Any text editor can create the file at any
time!
The Modem Doctor is copyrighted by Hank Volpe. The Shareware
Version of this program may be distributed on Bulletin Board
Systems or in Public Domain Libraries as long as a Fee is
not charged for its duplication or acquisition (except for
BBS systems that charge a user fee for system access).Under
no conditions can anyone accept payment for the Modem
Doctor but Hank Volpe or agents authorized for resale by
Hank Volpe. The Modem Doctor is distributed on as "As-is"
basis, with no warranties for usefulness or suitability
expressed or implied. Users of the Shareware version are
granted a limited license to use this program.
Section 2. Starting MDR
------------------------
The Modem Doctor has been designed to work with PC-Type
serial ports and "AT" Instruction Set (so called Hayes
Compatible[++]) Modems. The Modem Doctor requires at least 1
serial port to Operate. MDR is written to run under MS or PC
DOS 2.2 or higher, requires a MDA or CGA adaptor and at
least 90K of program memory. When MDR is started, it will
use the last text mode that the display adaptor was in
(Color or Black /White). MDA or CGA are the two execution
modes regardless of what kind of adaptor is in use.
The Modem Doctor Version 3.0 Documentation Page 4
Copyright (c) Hank Volpe 1989,1990
Code has been included to work with hardware-incompatible
display adapters as long as they are at least IBM-PC Bios
compatible. This is operator selectable at runtime. To start
MDR, type MDR from the dos prompt. If you wish to use the
Bios compatible mode instead of direct display writes, start
the program using the Bios switch ; MDR /B
Registered Versions 3.0 and higher also can be run to
quickly program and setup a Modem. To use this mode start
the program with the setup switch ; MDR /S (see Section 3).
Section 3. First Time Setup
---------------------------
MDR checks to see what hardware is available and reports its
results to you. Displayed on the bottom line is the serial
number unique to each copy Press any key to continue.
-[ ports ]-- |
| Use COMM 1 |
| Use COMM 2 |
| Use COMM 3 |
| Use COMM 4 |
---------------
Next, you are instructed to pick from a list of valid Comm
ports. The only ports that are listed are valid ports that
MDR found when it first started. The Registered Version
allows you to add ports that are not "standard" ports,
(check the section on Login). Use the arrow keys to find
your selection, and then press return to select.
-[ Baud ]--
| 300 BPS |
| 1200 BPS |
| 2400 BPS | *
| 4800 BPS | *
| 9600 BPS | *
| 19200 BPS | *
| 38400 BPS | *
-------------
*=Registered Versions Only
A window now opens showing you valid Comm port speeds.
Select a speed from this menu. Please note, don't select a
speed faster than your modem can handle. The reason for
faster speeds is so communication links can also be tested.
Use the arrow keys and press return to make your selection.
-[ Select an Option ]--------------
| Test Modem / port 1 to 300 BPS |
| Test the UART Hardware Only |
| Don't set up modem, return to Menu |
-------------------------------------
The Modem Doctor Version 3.0 Documentation Page 5
Copyright (c) Hank Volpe 1989,1990
At this point you are in the options menu. If you select
Test Modem, a series of commands and tests will be performed
to make sure the modem is on line and running. If you select
Test UART Hardware, only the 8250 UART will be tested. The
modem will not be setup. This selection is useful only if
you wish to test an RS-232 line or a "dumb" modem.
Selection 3 aborts to the main menu. (NOTE: Version 3.0
includes new "HOT-KEYS" to force the Modem Doctor to believe
you are using a Modem with a Microprocessor and for changing
the baud rate. Read Section 4 on the menu system for more
details).
A. Test Modem/ UART
---------------------
Preliminary Diagnostic Checks of Hardware
-----------------------------------------
A 16550AN Uart has been detected
Testing Modem Microprocessor
----------------------------
Modem Microprocessor Command Bus Active
Modem reports a 9600 bps Modem installed
Modem Microprocessor Accepts Setup Commands
Modem Microprocessor ON-LINE
Modem - UART Status appears correct
Press any key to continue
Above is displayed then normal test results with a modem.
First step tests the UART to Modem hardware. If any
connection errors are discovered, they are reported to the
screen. If no errors are detected, the Modem Doctor will
check to see what type of Uart is installed. There are
differences between the different types of Uarts, and the
Modem Doctor uses this test to determine how to test the
Uart and what registers to display to the screen. Next, the
the modem command bus is tested and if its compatible, the
modem ID information is queried from the Modem Processor.
Finally, the modem is setup for diagnostics. Note: These
setup strings do not overwrite any non-volatile storage. If
all is ok, all the UART registers and the First 16 Modem S
registers are displayed. This display is not shown the next
time you log in a Comm port unless you press the space bar.
If the modem does not respond to certain parts of the tests,
error messages are reported.
The Modem Doctor Version 3.0 Documentation Page 6
Copyright (c) Hank Volpe 1989,1990
Testing Modem Microprocessor
----------------------------
Modem Microprocessor Command Mode Not Detected
Software Reset Initiated
This message is displayed if the modem did not respond the
first time for a query to its status. This could happen for
any number of reasons, including that the modem was still on-
line and not in the command mode. A soft-reset is performed,
which essentially tries to wake the processor up.
No Response...resetting Modem Microprocessor ...attempt #1
No Response...resetting Modem Microprocessor ...attempt #2
No Response...resetting Modem Microprocessor ...attempt #3
After 3 soft-resets, the Modem Doctor assumes that the modem
is jammed and needs a hardware reset. A hardware reset is
the program equivalent of turning the modem on and off
again. This is the only way to reset some internal modems
that get "jammed" when the computer is first turned on.
Clearing a "jam" usually takes no more than 2 attempts.
Trying a Hardware reset of the Modem Microprocessor
The Hardware reset is performed, and again the modem
microprocessor is strobed for its status.
Software Reset Initiated
After a hardware reset, a soft reset is performed again,
attempting to wake the processor up. If this fails, the
following message is displayed;
Modem Microprocessor Did Not Accept Setup Commands
Trying a Hardware reset of the Modem Microprocessor
After one more attempt at waking the modem up, the Modem
Doctor assumes that the modem is not compatible and based
on the status given it by the UART, it will report if the
device is off or not connected.
WARNING..This unit does not have a Compatible Modem attached
WARNING..The Modem Device appears to be off or not connected
The registers are now displayed for diagnostic tests, and a
conclusion based on the status of the registers is
displayed. There are many reasons why the modem/UART could
fail. See the error code section for details. If the UART is
fine, but the modem is not compatible, the program will
tell you that the UART hardware tests ok and display this in
a window to the right of the register display.
The Modem Doctor Version 3.0 Documentation Page 7
Copyright (c) Hank Volpe 1989,1990
Note: The reason for testing the Modem command set so
extensively is so there can be no doubt about the Modem
accepting commands. You can force The Modem Doctor to
believe it has a Modem with a Compatible Microprocessor by
using the "HOT-KEY ALT-F". See Section 4 about Menu
system commands.
B. UART Tests
---------------
The UART test is performed every time either the Modem or
the UART test is selected. Essentially, the UART test
programs all of the registers of the UART and looks to see
that the correct values have been placed in them. If any one
of the registers fails to set, the Modem Doctor will display
all of the registers and a diagnostic message. After that,
it looks to see that an RS-232 loop is active. If not, it
displays an error message saying that the loop is either
disconnected or a register in the UART is defective. If all
checks well, the type of Uart chip that is installed is
returned. The type of Uart chip is important for the way the
Modem Doctor will test and display the Uart. Essentially
there are 3 types it can detect;
8250-B
This is the original Uart installed in many PC's and Serial
Port add-on cards.
16450/8250-A
This is an upgraded Uart that fixes a bug in the interrupt
enable register of the 8250-B and also tri-stated the OUT2
pin of the chip during loopbacks. It also adds a scratch-pad
register as the highest register. This register is tested
by the Modem Doctor but not displayed because it never has
what you would consider as a "correct" setting. The 16450 is
used primarily in 80286 (AT) systems because of its increase
in throughput over the 8250-B
16550
This chip is essentially a faster 16450. However, it cannot
be used in a FIFO buffering mode, but it does allow for a
programmer to use multiple DMA channels and thus increase
throughput on an AT or higher class computer system.
16550AN
This chip is a faster 16450 with a built in Transmit and
Receive FIFO buffer. It also allows multiple DMA channel
access. You should see this chip in your 80386 or RISC
type machine. You should also consider installing this
chip if you do any serious communications at 9600 bps
or higher. Whenever a 16450,16550 or 16550AN is displayed,
different diagnostics and/or different register mnemonics
are displayed. The 16550AN's ability to enable and disable
The Modem Doctor Version 3.0 Documentation Page 8
Copyright (c) Hank Volpe 1989,1990
FIFO mode is also tested. In any case and with any Uart,
each register is checked for proper values. If anyone of
them fail, a window will open and display a possible
cause for the problem.
Preliminary Diagnostic Checks of Hardware
-----------------------------------------
Testing UART Hardware Only
--------------------------
A 8250-B Uart has been detected
Modem - UART Status appears correct
The first time through these tests, the registers will
display for diagnostics. Unlike the modem tests, only the
UART registers are displayed. From then on, if the test
results are correct, you will be prompted if you wish to
have the registers displayed. If a test fails at any time,
you will always see the registers displayed along with an
appropriate diagnostic message.
C. Return to main menu
----------------------
Selecting this returns you to the main menu, this allows you
to change an entry made in error without having to wait for
the diagnostic checks to fail. In any event, after any of
these tests have been run, you will then enter the Modem
Doctor's Main Menu.
Section 4. The Main Menu
----------------------------
-------------------------- The Modem Doctor -----------------
|Log-in Regs Carrier Loopback Manual Setup End Program|
-------------------------------------------------------------
All of the above selections are toggled using the arrow keys
and selected using the return key. Pressing the down arrow
displays a brief message about what each function does.
Log-in COMM ports
------------------
The ROM-BIOS only looks for COMM ports 1 and 2.
Use this section to manually log-in a COMM port
that cannot be detected by DOS. Entries are also
good after you quit
UART Register Diagnostics
-------------------------
This test section can be used to check the
contents of an 8250 UART and the 8259 Interrupt
Controller mask register.
White = Active, Gray = Not Active
The Modem Doctor Version 3.0 Documentation Page 9
Copyright (c) Hank Volpe 1989,1990
Carrier Mode Tests
------------------
This tests runs a AT Instruction Set modem in an
test of the Carrier Originate and Answer frequencies.
An AT Instruction Set Modem or a modem with Manual
Carrier selection is required
Loopback/ UART Tests
------------------
This test is designed to check out a RS-232 COMM
port for proper operation. No Modem is required for
this test however this test is not for an Internal
Modem, although it can be run as a test of the
command channel.
Manual Interactive Tests
-------------------------
This test is designed to check out the command
channels and user interface to a AT Instruction Set
Modem. You can also use it with an RS-232 loop or to
send your own commands.
Setup Diagnostics
-------------------------
Use this test section to return to the setup mode
to change a port assignment or a Baud Rate to a new
value. Only Logged-in Comm ports can be accessed.
Exit Program
-------------
Quit the program, all vectors and interrupt
tables are restored.
4.01 Hot-Key selection
----------------------
In addition to these menu selections, there are two Hot-Keys
that are active at nearly all times in the Modem Doctor. The
ALT-B combination can be used to change the baud rate from
the main menu and from inside the Manual test section. A
window will pop-up and you can pick your desired serial port
speed. This can save a lot of time when you wish to test a
modem at various speeds. Using the Setup / Test Modem & Uart
mode is the safest way (because it verifies the modem
microprocessor accepts commands properly at the selected
speed), however if you use the ALT-B command, you will take
a short-cut that can help you when testing your modem.
The Modem Doctor Version 3.0 Documentation Page 10
Copyright (c) Hank Volpe 1989,1990
The other Hot-Key active from the main menu is ALT-F, or
FORCE Micro on-line. Actually, there is no "force" involved.
By pressing this key,you force the Modem Doctor to believe
there is a AT Instruction set compatible modem attached.
This can be handy for troubleshooting a modem that doesn't
work properly at certain speeds or under certain conditions.
The Setup Test Modem & Uart section will not allow any AT
Instruction set Carrier tests on modems that it cannot
properly setup. The ALT-F combination bypasses this and
allows such testing. When you press ALT-F, you will notice
the Status Bar will say that a modem microprocessor is on-
line.
4.1 Login In Comm ports
-----------------------
When you select this menu, you are offered these choices
--[ Comm port Login ]-----------
| Let me Auto Detect COMM ports |
| You Manually Enter COMM ports |
| Return To Main Menu |
---------------------------------
Option 1 repeats what the Modem Doctor does when you first
begin to run the program. Option 2 allows you to enter a
"non" standard port address and assign one of the two
Interrupt lines to use with the UART. Option 3 returns to
the main menu.
4.11 What do IRQ's and COMM Ports do ?
---------------------------------------
Each time a character is received by a modem, it has to get
the attention of the computer by raising an Interrupt
Request Line (IRQ). PC type computers have 8 of these lines,
AT type computers have at least 16. The 8259 Interrupt
controller chip handles these requests for attention. By
design, COM1 uses IRQ4 and COM2 uses IRQ3. IRQ7 is
assigned to a printer, IRQ5 to the Hard Drives. It is
possible to use COM1 and COM2 or COM3 and COM4 at the same
time, but you cannot use COM1 and COM3 or COM2 and COM4 at
the same time because these share IRQ lines. If you needed
to use 3 or more COMM ports at the same time, you would need
to use another IRQ line. The best bets are IRQ7 and IRQ5,
because they may be available when you need them. IRQ7 is
really only needed by programs that use printer interrupts
(background type spoolers for example). IRQ5 is used by
fixed disks. It may or may not cause a conflict if you use
this IRQ line with your modem. PC type computers are quite
limited because they only have 8 IRQ lines and most are
reserved. AT type computers have 16 IRQ lines. A good tip
would be to consult your Hardware manual to find out if you
can or can't use these other IRQ's. However, if you do not
need to use 3 or more COMM ports at one time, then it is
best to stick to the reserved IRQ4 and IRQ3 for all of your
activity.
The Modem Doctor Version 3.0 Documentation Page 11
Copyright (c) Hank Volpe 1989,1990
4.12 Port assignments and their meaning
---------------------------------------
Like IRQ lines, certain Port addresses were reserved to work
with the PC's external hardware devices. Two of these were
reserved by all manufacturers; 3F8 (HEX) and 2F8 (HEX).
Although only two COMM ports were supported by the original
ROM-BIOS, there are two additional port memory locations
available for use by MS-DOS and PC-DOS applications. These
reserved Port addresses are 3E8 (HEX) and 2E8 (HEX). Most
internal modems come with these 4 ports as selections along
with several IRQ line combinations. There is a "quirk" in
the way that the ROM-BIOS logs in these ports. If the Power
on self-tests (POST) do not find a 3F8 serial port but they
do find a 2F8, then the 2F8 serial port is mistakenly
assigned to COM1. To add to this, the reserved IRQ line for
COM1 is IRQ4. But this serial Port of 2F8 is using COM2's
address, which means it needs IRQ3 instead of IRQ4. So, if
you are trying to use Basic, Pascal, or DOS for COM1
operations, the serial port or modem will not be able to
work. The general rule thus is "No COM1 without COM2". The
Modem Doctor when it is run will correct this login problem
and correctly assign COM2's port address to COM2, and it
will also leave the ROM-BIOS logged in COM1 (actually COM2
again) at COM1. People who have such setups will see the
Modem Doctor state there are two COMM ports, but actually,
there are two different assignments for the same port.
These addresses for PC's are standardized in order for
Communication programs to properly work. As stated above,
the industry standards are;
COMM 1 3F8 COMM 2 2F8 COMM 3 3E8 COMM 4 2E8
IRQ4 IRQ3 IRQ4 IRQ3
COMM 5 3F8 COMM 6 2F8 COMM 7 3E8 COMM 8 2E8
IRQ7 IRQ7 IRQ5 IRQ5
The port addresses for serial ports (1-4) are held in a
reserved area of Memory. The "base port" of each of these
UARTS is saved in a distinct area. When you first start the
Modem Doctor, the program checks these locations to see if
there are any Comm ports already logged in by Dos. If not, a
search is conducted for the PC's default Comm 1 and Comm 2
port values and these are logged in. Next, a search is
performed for the other industry standard Comm ports. Some
PC's already log these in, however IBM-PC's and those that
mimic exactly their ROM-BIOS routines do not log in a COMM 3
or a COMM 4. The Modem doctor will, and as a side benefit,
these stay logged in until the next warm or cold boot is
performed on your computer. Why would dos not log in a
port? Well, some multi-tasking programs overwrite this area
to prevent "swapping" of communication programs and it is
The Modem Doctor Version 3.0 Documentation Page 12
Copyright (c) Hank Volpe 1989,1990
possible that they might not be properly restored on exit.
Next, a search is made for the Custom Comm ports 5-8. These
ports are not held in DOS at all, but are held in program
memory by the Modem Doctor after a user logs the port in
using the Manual log in mode (see below). If one of these
Ports is found, it will be added to the Comm Port option
menu for you to use when you test the Modem. The reason for
the custom ports is to help users who are using non-standard
interrupt lines (IRQ7,IRQ5). Unlike the DOS logged-in ports,
these assignments disappear when the Modem Doctor is exited.
The Modem Doctor follows the accepted arraignment of these
Comm Port /IRQ line pairings. However, you do have full
control at all times over all Port addresses and IRQ
assignments and can change them using the Manual Login Mode.
As far as the 2 Options presented by the Login Mode, option
2 is the only real option available. Please use it with
caution. The only real need for this option is for logging
in a COMM port that does not use any of the listed industry
standards as its base port address or IRQ line assignments.
Consult your serial port or Modem's user manual to make sure
you enter the exact port address and select the correct
Interrupt line to use with it. Otherwise the Modem Doctor
will not recognize or be able to test any device hooked to
this port. Protection is included in this routine to keep
someone from accidentally entering a port that is used by
the system board, display adaptors, or fixed disk adaptor.
Entering any of these values, or an error, will result in
the display;
"WARNING...RESERVED port...RETRY ENTRY"
After running Option 1 or 2 , you must tell the Modem Doctor
which COMM port you wish to use so that testing can begin.
Pressing the ESCAPE key is the same as Option # 3 and
returns you to the main menu.
4.13 Testing defective Ports
----------------------------
Whenever the Modem Doctor checks to see if a port is working
properly, it checks the status of several registers. If a
Uart Chip appears "dead", the Modem Doctor will tell you
that the port was not "found". Previous versions of the
Modem Doctor would not allow a defective serial port to be
logged in for testing. Now you can use the Manual mode and
override this setting. If you tell the Modem Doctor for
example to use serial Port 2F8 as COM2 and you do not have
a COM2, the message "COM2 not Found" will be returned with
an option "Override [Y/N] ?". Answering "Y" will force the
login of this port. Certainly there is no benefit to
testing a non-existent port, but a port that is defective
may not be logged-in. So, you now have the option to test
this defective port hardware to pinpoint a problem. Combined
with the register display and diagnostics, you will most
likely be able to pin-point any Uart problem quickly and
easily.
The Modem Doctor Version 3.0 Documentation Page 13
Copyright (c) Hank Volpe 1989,1990
4.2 Regs
-------------
The register display section can be an invaluable diagnostic
tool. What this does is "poll" all of the status registers
of the UART, and the Interrupt Controller to tell you
exactly what is going on. When you use the setup mode, the
Modem Doctor checks all of these registers for correct
information. If something wrong is discovered, a warning
is displayed on the screen telling you what the Modem Doctor
believes is wrong. Many different error conditions are
checked, see the error code section for a listing. Each
register contains a Mnemonic for each one of the data bits.
Bits that are a logic low ( = 0) are displayed in low
intensity, those that are a logic high (= 1) are displayed
in high intensity. On a color monitor, this is easy to see.
On a Mono Monitor, make sure you have the brightness and
contrast controls properly adjusted to see the difference
between the two status conditions.
-[ Line Control Register ]----------
| DLB STB STP EPS PEN STB WS1 WS0 |
------------------------------------
This register controls many of the setup characteristics of
your UART and how it behaves to your PC. This register is
responsible for setting baud rate, setting break code
transmission, parity, and the length of the serial stream
word. When you enter the setup mode,
DLB Divisor Latch Used to access the baud rate
registers. Should be 0 for
the Modem Doctor
STB Set Break If High, the modem transmits a
break signal, should be 0
normally.
STP Stick Parity Should be 0 normally
EPS Even Parity select High = Even Parity..should be
0 normally
PEN Parity Enable Enable Parity checks, should
be 0 normally
STB Stop Bits Number of stop Bits, should be
0 normally to Indicate 1 stop
bit character only.
WS1 Word Length Select 1
WS0 Word Length Select 0 These two bits are used to
determine the serial data
word length. Both should
be High normally to indicate a
length of 8 bits.
The Modem Doctor Version 3.0 Documentation Page 14
Copyright (c) Hank Volpe 1989,1990
-[ Line Status Register ]-----------
| TSE THE BI FE PE OE DR |
___________________________________
The line status register reports error conditions that might
have occurred between the PC and the UART.
TSE TX Shift Register A High indicates that all
characters Empty sent to the
UART were transmitted. Should
be High Normally.
THE TX Holding Register A High indicates that the UART
can now Empty accept a new
character from the PC.
Should be High Normally.
BI Break Interrupt A High indicates that a break
signal was received. Should
be Low Normally
FE Framing Error A High indicates that a serial
data train did not have a
proper stop bit. Should be Low
Normally.
PE Parity Error A High indicates that the
received serial data's parity
did not match what the UART
was programmed to receive.
Should be Low Normally.
OE Overrun Error A High indicates that a
character in the receive
buffer was not read by
the PC in time, and another
character overwrote and
destroyed it. Should
be Low Normally.
DR Data Ready A High indicates that a
character has been received
and is ready to be read
by the PC from the Receiver
Buffer. Should be Low
normally for these test, but
can vary while data is coming
in from the Modem.
The Modem Doctor Version 3.0 Documentation Page 15
Copyright (c) Hank Volpe 1989,1990
-[ Modem Control Register ]---------
| LP OT2 OT1 RTS DTR |
------------------------------------
The Modem Control register handles all of the interfacing
between the UART and the modem. Only 5 signals are
needed to handle this
LP LOOP A High indicates that the
Loopback digital diagnostic
has been activated. This
feature only works with 8250
UARTS or those that are 100%
Compatible. This is used in
the Digital Loopback test.
OT2 OUT 2 A High enables the UART to
generate interrupts. A Low
disables interrupts. This
should always be high for
testing purposes.
OT1 OUT 1 On 100% compatible modems, a
High on this pin will perform
a Hardware reset of the modem
in some compatible designs.
Normally this is a Low.
RTS Request to Send A Handshaking signal that is
used by some modems to enable
data transfer between the
Modem and the UART. Should be
High for testing purposes.
DTR Data Terminal Ready A Handshaking signal that is
used by some modems to enable
data transfer between the
Modem and the UART. Should
be High for testing purposes.
The Modem Doctor Version 3.0 Documentation Page 16
Copyright (c) Hank Volpe 1989,1990
-[ Modem Status Register ]----------
| RLS RI DSR CTS DRD TER DDR DCS |
------------------------------------
The Modem Status Register returns the status of the control
signals sent by the modem to the UART.
RLS Received Line Detect A High indicates that a
carrier has been received by
the modem. When the Analog
tests are run, this should
be High. If it is not, it is
still possible that the Modem
is ok, however the cable from
the Modem to the UART (for
externals only) might not have
a complete circuit due to
faulty wiring of the RS-232
cable. This signal is very
important for some
communications programs to
operate properly.
RI Ring Indicator A High indicates that the
modem detected a Ringing
signal on the phone line.
DSR Data Set Ready This is part of the DTR/DSR
Handshaking pair that is used
by some modems to control
the flow of data. Should
normally be a High.
CTS Clear to Send This is part of the RTS/CTS
Handshaking pair that is used
by some modems to control the
flow of data. Should normally
be a High.
DRD Delta Received
Line Signal Detect A High indicates that the
Received Line Signal has
changed state.
Some Communications programs
use this also as an
indication that a Carrier
was detected by the modem.
TER Trailing Edge
Indicator A High indicates that the Ring
Indicator changed state. Some
Communications programs use
this as an indication that
the phone as Rung.
DDR Delta Data Set Ready Indicates that the DSR signal
has changed state.
DCS Delta Clear to Send Indicates that the CTS signal
has changed state.
The Modem Doctor Version 3.0 Documentation Page 17
Copyright (c) Hank Volpe 1989,1990
If a 8250-B / 16450 or 8250A Uart was detected, the
following is displayed
-[ Interrupt ID Register ]----------
| ID1 ID0 ITP |
------------------------------------
The Interrupt ID Register is used to tell the CPU what kind
of interrupt occurred.
ID0 Interrupt Bit 2
ID1 Interrupt Bit 1 These two signals are a binary
code which can be read by the
CPU to tell what kind of
interrupt occurred. Both Bits
high indicates an error
occurred or a Break Interrupt
was received. Bit 2 high and
Bit 1 low indicates that data
is ready to be read by the
CPU. Bit 1 High and Bit 2 low
indicates that a Ring signal
or Carrier signal was
received. For testing
purposes, only the Data ready
mode is used.
ITP Interrupt Pending A Low indicates that an
interrupt has occurred. For
testing purposes, this
should always be high if data
was successfully read by the
Modem Doctor. If it is not,
then an interrupt did occur
but the CPU did not respond.
Suspect a problem with an
interrupt Controller Chip or
the UART interrupt generating
capability. If a 16550 or
16550AN chip was detected, the
register selection uses the
enhanced register display
The Modem Doctor Version 3.0 Documentation Page 18
Copyright (c) Hank Volpe 1989,1990
-[ Interrupt ID Register ]----------
| FEM FEL ID2 ID1 ID0 ITP |
------------------------------------
FEM FIFO Enable MSB This is the Most significant
Bit of the FIFO Register. It
should be high on both the
16550 and 16550AN if the FIFO
Buffering is enabled. Normal
Modem Doctor status shows this
as a Logic Low (unless testing
is performed).
FEL FIFO Enable LSB This is the Least significant
Bit of the FIFO Register. It
should be a high on the
16550AN only! The 16550 always
displays this bit low. Again,
the normal Modem Doctor status
will show this as a Logic Low
(unless testing is performed).
ID2 FIFO Timeout This signal is raise high by a
16550AN to indicate that it is
holding characters for the CPU
to read, but it is less than
what the CPU has requested to
be interrupted for. The FIFO
buffer can be as deep as 14
characters. If only 8 have
come in, the CPU will not be
interrupted. The 16550AN is
programmed to interrupt after
a period of time has gone by
during which no characters
were received in order to
force the CPU to get what it
is currently storing. Normal
operation should keep this
line low, if it is high at any
time there is a problem with
the UART.
The Modem Doctor Version 3.0 Documentation Page 19
Copyright (c) Hank Volpe 1989,1990
-[ Interrupt Enable Register ]------
| ESI ELI ETI ERI |
------------------------------------
The Interrupt Enable register is programmed to allow certain
types of interrupts to occur.
ESI Enable Status A High causes the UART to
generate an Interrupt whenever
RI or RSD signals in the Modem
Status register go high.
Should be low for testing.
ELI Enable Line A High causes the UART to
generate an Interrupt
whenever an error or break
interrupt is detected in the
Line Status Register. Should
be low for testing.
ETI Enable Transmitter A High causes the UART to
generate a Holding Register
interrupt whenever the THE
signal of the Empty Interrupt
Line Status register goes
High. Should be low for
testing.
ERI Enable Receive Data A High causes the UART to
generate an Ready Interrupt
whenever Data is ready to
be read by the CPU. The DR
line of the Line Status
register going to a high
state generates this
condition. This signal should
be High for testing purposes,
since it is the only
interrupt needed by the Modem
Doctor.
-[ Interrupt Mask Register ]--------
| IQ7 IQ6 IQ5 IQ4 IQ3 IQ2 IQ1 IQ0 |
------------------------------------
The Interrupt Mask Register is contained on the 8259
Priority Interrupt Controller on your Computer's
Motherboard. Each one of these Hardware Interrupts
corresponds to an external device.
IQ7 Printer Interrupt (can be used by Custom COM5 or COM6)
IQ6 Floppy Disk Interrupt
IQ5 Hard Drive interrupt (can be used by Custom COM7 or
COM8)
IQ4 COM1 Interrupt (also COM3)
IQ3 COM2 Interrupt (also COM4)
IQ2 reserved by IBM (Gateway to second 8259 on AT's)
IQ1 Keyboard Interrupt
IQ0 Timer Interrupt
The Modem Doctor Version 3.0 Documentation Page 20
Copyright (c) Hank Volpe 1989,1990
Under Normal Conditions, IQ0,IQ1 and IQ6 should be lit,
along with IQ4 if testing COM1 (or COM3) or IQ3 if testing
COM2 (or COM4). In addition, other lines could be lit
depending on your computer. The only line the Modem Doctor
looks for is the IQ4 or IQ3 lines (depending on which serial
port you are testing).
4.3 Carrier Tests
-----------------
The Carrier test section is used to test your modem's
ability to detect a carrier, demodulate signals on the
originate frequency and answer frequency, and to properly
control the RLS (Received Line Signal) and CD (Carrier
Detect) Modem Status/Control lines. All of these are
essential elements for good data communication. When you
select carrier tests, a pull down menu is displayed. Option
1 prompts you to run the Carrier tests. Option 2 offers you
the chance to select a custom modem driver. Option 3 allows
you to return to the main menu (pressing ESCAPE also does
the same thing as option 3).
4.31 Modem Driver Modules
--------------------------
Although your AT Instruction set modem is based on a defacto
standard developed by Hayes, there are several "supersets"
of this instruction set for various modems. Currently, the
Modem Doctor supports 3 different software Modem Drivers for
testing; Generic Compatible, &T0 instruction set, and
Courier HST/V.32. When the Modem Doctor is running the setup
mode, it queries the Microprocessor for its type
identification. Based on this information, a Modem Driver is
selected for use. Basically, all 2400 bps and lower modems
are assigned the Generic Driver, and all 9600 and higher
modems are assigned the Courier HST/V.32 driver. The &T0
instruction set modems are tested in a different manner with
a different set of instructions. Previous versions of the
Modem Doctor would automatically switch to the &T0
instruction set if the modem was a 2400 bps modem and if it
failed to properly detect a carrier during testing. This
function is still built into the Modem Doctor, but you can
optionally select the &T0 driver yourself before beginning
your testing in order to speed things up. Auto-selection
added about 10 seconds a pass that can now be eliminated.
If you desire to select the &T0 set for your modem instead
of letting the Modem Doctor do it for you. NOTE: Don't
select this instruction set unless you know for sure that
your modem is 100% instruction set compatible with the Hayes
2400 or 2400B. Hayes 1200 bps and lower, and almost all
other 2400 bps and lower modems use the Generic Driver. You
will find that 99% of all modems will work properly with
this assignment, in fact, if you disable all data
compression and Fixed link assignments from any high speed
The Modem Doctor Version 3.0 Documentation Page 21
Copyright (c) Hank Volpe 1989,1990
modem (including the Courier's), the Generic Driver will
test these modems properly also! This allows people with
high-speed modems that are not supported currently to use
the Modem Doctor for testing. If you have a high-speed modem
that is not supported, you can use a Combination of the
Manual mode and the Generic Modem Driver to test these
modems also.
4.32 Types of Carrier Tests
-----------------------------
The Carrier tests are designed to test your modem under
actual use conditions (minus a telephone line). Your Modem
uses two different frequency bands for communication. These
are the Originate and Answer frequencies. AT Compatible
modems can select these under command of the Modem Doctor
via the appropriate Modem Driver module. So called "Dumb"
Modems have front-panel switches that you must use to
properly test the modem. The Modem Doctor supports both
types of tests, one of which is automatically selected by
the Modem Doctor depending on the hardware it detects.
4.33 AT Instruction Set Tests
-----------------------------
AT Instruction Set Modem Test - If you selected the Test
Modem/UART option from the setup menu and a Modem with a
compatible Microprocessor was detected, or if you have
forced the Modem Doctor to use the AT instruction set tests
via the Hot-Key ALT-F, the Modem Doctor will test the
Originate and Answer frequencies of your modem
automatically. Before running this test, make sure you have
disconnected the modem from the telephone line, because the
modem will go off-hook and sometimes the dial-tone will
interfere with testing. If you press ESCAPE in this menu,
you return to the main menu. Any other key continues.
You will be prompted to enter a "Loop Count". If you select
a count of 1, you will be able to hear the connecting tones
on your speaker. If you select a count greater than 1, then
the speaker is turned off. After you make your selection,
two windows will open on your screen. One contains data that
is being sent to the modem, the other Data that has been
received by the modem. All of the characters from Binary 0
to Binary 255 are transmitted. Some of these will look
strange because they are characters of the Extended
Character set. The Modem Doctor takes a great deal of care
in preserving the normal condition of your modem before
testing, and sends all the character strings necessary to
test without disturbing any non-volatile memory settings. If
you have an external modem, you will see the data being sent
and acknowledged before testing begins. While it is setting
up, the Modem Doctor tells you what is going on,
including that the Modem is reset, that commands are being
sent, and that it is waiting for a carrier. The Modem Doctor
waits up to 15 seconds for either the word CONNECT or the
The Modem Doctor Version 3.0 Documentation Page 22
Copyright (c) Hank Volpe 1989,1990
RLS signal to go active. If this does not happen, the Modem
Doctor switches to the &T0 command set that is used by Hayes
2400's and several other clones. This test is just as valid
as a full carrier test and verifies both the modem and the
Uart signal paths as does the traditional carrier test. If
you switch to this mode, you will be informed via the screen
and the message "CARRIER NOT DETECTED" will be displayed.
Also, if you have an external modem, you might see the
"Modem Ready" light flashing throughout this test. If you
selected the &T0 instruction set yourself from the Modem
Driver selection menu, then the &T0 set will be used
exclusively. This selection s mainly a convenience for some
users (because the Auto-detection method takes a little
longer), however it will not test any other kind of modem
properly. If you are unsure, let the Modem Doctor figure it
out for you.
Note, if you select more than 1 itineration and change you
mind, press ESCAPE anytime during the test. At the next
available loop-repeat time the Modem Doctor Will abort
testing and give you your current status.
4.34 Uart or Dumb Modem Tests
-----------------------------
This test works the same as the AT Instruction Set Modem
test with two main exceptions. First, Your modem must be
able to generate a carrier on its own on the answer and
originate frequencies. Most external "dumb" modems have
front panel switches for this function. Most are marked as
AL (for Analog Loopback). If your modem can generate this,
answer yes and follow the prompts on the screen. All
testing is performed as above, except you setup the modem
instead of the Modem Doctor using its Modem Driver
software. Whenever the Modem Doctor is working with the
Micro in the "Off-line" mode, the Dumb mode tests are used.
You are prompted if your modem can generate a carrier.
Answer yes to start the testing. You are then told to place
your modem in the Analog Loop mode and force the carrier
detect on. Most dumb modems will light the CD light on the
front pane of the modem when you press the AL switch. This
CD light sends a RLS (Received Line Signal) status word to
the Uart. The Modem Doctor looks for this before it will
allow testing in this dumb mode. If your modem cannot
generate a carrier indication, you can still test an analog
loopback using the Loopback function in the registered
version and select the Analog Loopback tests (this is
explained later in the documentation).
The Modem Doctor Version 3.0 Documentation Page 23
Copyright (c) Hank Volpe 1989,1990
4.35 Error Messages
-------------------
If A RLS (Received Line Detect) signal is not received
before testing begins, this indicates that either A Carrier
is not being generated (or properly received in self test)
by the modem, or an RS-232 Cable to an external modem is
improperly wired. Although RS-232 loops will work fine
without an RLS signal being wired, there is no way for the
modem Doctor to detect on a Dumb Modem if a carrier was
generated. On a AT Instruction Set Modem, the Modem Doctor
alternately looks for the word "CONNECT" to be sent from the
modem if there is no RLS signal available. If you wish your
all of your communications programs to work properly, you
should get a cable with this signal wired. If an Error is
detected during the Analog test, the error Counter is
incremented. There are two error counters; One is used for
the Originate Mode, and the other for the Answer Mode. If
you receive an error, it could be due to a problem with a
UART or a Modem at a certain Baud Rate. Try testing at other
Baud rates to determine if the errors repeat. Also Errors
could occur on only the Originate or the Answer frequency.
This is more prevalent at higher baud rates. Finally, make
sure that the modem was disconnected from the Phone line
before testing. The Dial-tone interferes with some modems.
One other possibility exists, that there could be a problem
with a cable or interrupts not properly being generated or
properly handled by the CPU. Run the Digital/Loopback
tests and if the problem repeats, you might have a bad UART
or motherboard problem. Although it is unlikely, if power is
removed from the modem or a cable falls off (or who knows
what else), the Modem Doctor waits a pre-determined period
of time for an interrupt to occur. If none is detected, the
warning "Modem Queue Failure" or "Modem Receiver Failure"
will be displayed in one of the windows. These might also be
displayed if the Modem never acknowledged a character being
transmitted, or never sent one back. Again, the only
conditions that would cause this would be a cable being
removed between the modem and the Uart, the power being
removed to the modem, or the modem "blowing up" via some
unnatural means during the test. If the RLS (Received Line
Signal) is constantly active from the modem, the Modem
Doctor will tell you that you might have a problem with a
cable or the modem and that the test results might not be
valid. Reason for this is that the Modem Doctor never did
detect a carrier because the UART said it was already there.
This can be traced in nearly all cases to the Modem. Change
the setting of the Modem to let the Carrier Detect (CD) act
normally. It should never be set to be forced on for a
PC. If so, not only the Modem Doctor, but other
communications programs will not operate properly.
The Modem Doctor Version 3.0 Documentation Page 24
Copyright (c) Hank Volpe 1989,1990
4.4 Loopback Tests
-------------------
The Loopback tests were designed for two purposes. First, to
test an RS-232 loop including cables that are properly
terminated with a loopback plug, and second, to run a
digital loopback test on 8250 and 100% Compatible UARTS.
Additionally, the Analog portion of this test
can be used to test a dumb modem that does not generate a CD
(Carrier Detect) signal when the AL switch is thrown on the
front panel. Selecting Loopback and pressing return fetches
this menu;
-[ Loopback Tests ]-----------
| Analog Loopback using a PLUG |
| Digital Loopback 8250 UARTS |
| Loopback Plug Technical Data |
| Return To Main Menu |
--------------------------------
Analog Loopback tests require that you attach a Loopback
plug either to the back of the Comm port connector on your
computer, or at the end of a RS-232 Cable. This test is
designed for external Modems, however you could run this on
an internal modem as a test of the command channel's ability
to receive characters. Caution should be used on
internal modems, for some will fail this test. If this
happens, don't be concerned. However this test should NEVER
fail with a Loopback Plug, unless you were trying to drive
the line at an excessive rate. Remember, the faster the data
rate, the shorter the lines should be, and the faster the
computer should be to handle it. With a loopback plug on the
back of the serial port, speeds of 38400 bps should run fine
even on a slower PC. If you experience problems at 38400 but
not at 19200, chances are your hardware is fine (if you are
using an 8250-B). In extensive testing with PC's at 4.77
mhz, the original 8250-B performed flawlessly at 38400 bps.
Dumb modems can use this test also (as explained above and
in the section regarding Carrier tests). Digital Loopback
tests require that you have an 8250-B, 8250A,16450, 16550,
16550AN or other 100% compatible UART in your system. These
UART's have built-in diagnostics. If you are using a PC
compatible internal modem or a PC compatible Serial Card,
then you will definitely have a compatible Uart installed.
There is a design difference between the 8250-B and other
compatible chips in this series. Some of the differences
were explained above, but the important difference for the
Loopback test is the way the different Uarts will respond.
The 8250-B allowed its OUT2 signal to become active during
loopback testing. The OUT2 signal is used by PC compatible
machines to gate the interrupt signal off of the serial
board (or internal modem). Later designs (8250A, 16450,
16550,16550AN) tri-stated this line. As a result, the self-
The Modem Doctor Version 3.0 Documentation Page 25
Copyright (c) Hank Volpe 1989,1990
test diagnostics will not allow the interrupt signal to gate
off the board and interrupt the CPU. This would cause all
digital loopback tests on these improved chips to fail. The
Modem Doctor handles this by a brute-force read of the
Uarts. By sampling the Interrupt ID register, the presence
of an interrupt is detected, then the receiver buffer
register is read. This method is not as efficient as a true
interrupt-driven test would be, but it is accurate. The Uart
does generate the ID for an interrupt, the character is
pulled out of the Uart, its just that the presented speed on
the screen is not as fast as it should appear to be. When
running this test on an 8250-B, you will see the true speed
of the interrupt handling and processing. On others, you
will see the brute-force method. Each is an accurate test of
the Uart and valid at any baud rate selected. If this test
does not run, but yet the Analog test and all other tests
run fine, it means that you do not have a compatible UART
installed. Some UARTS that are not 8250's have a problem
entering this mode properly. If the test does not start, do
not be alarmed, because only 8250 and true compatibles will
pass this test. However this test will NEVER start and then
fail unless you do have a hardware problem. You should never
pick up a character error using this test. If you do, you
have a bad UART or CPU Motherboard Problem. Both Tests open
up windows (like the Analog test) and send and receive
characters to the UART. If you wish to know how to build a
loopback plug, select the Loopback Plug technical data
section. Pressing ESCAPE is the same as Option 4 and returns
you to the main menu.
4.41 Loopback Test Error messages
---------------------------------
Essentially the error messages for these tests are simple.
In the Loopback test mode, if a character is received
incorrectly, the error counter is advanced and a report is
issued at the end. If the Analog or Digital tests fail to
receive or transmit characters, the messages will explain
that either the Transmit Queue, the Receive Queue failed, or
that the Uart did not respond to the tests. The last message
may be displayed if you have a non-compatible Uart. If the
Uart fails to setup properly for the Digital Loopback test
(does not program its registers properly), a warning is
displayed that there is an error in one of the registers.
The message will explain what is wrong and what it
expects. See the warning message section for more details
The Modem Doctor Version 3.0 Documentation Page 26
Copyright (c) Hank Volpe 1989,1990
4.5 Manual
----------
As well written as the Modem Doctor is, there exists the
possibility that a Modem or a system might not be compatible
with the diagnostics. The Manual section allows you to send
your own string commands to the Modem, read back data, and
in fact you could use this as a Mini-communications program.
If you select this mode, a window opens with the banner
Interactive Mode. At the Bottom are listed the "Hot-Keys"
you can use;
ALT-B This opens a window for you to change the baud rate.
Note: if you are on-line with a service this might cause an
error between the computer and the modem. Off-line
conditions should work properly.
ALT-C Clears the screen. This only clears the window of
data, and leaves all your prompts.
ALT-R This displays the UART registers...handy for real-
time troubleshooting of RS-232 loops.
ALT-H Help..this displays the basic AT Command set
instructions that you could use to control your modem. Note
that this is only a basic set. Some modems have many
extensions to this, so for advanced work, consult your
owners manual.
ALT-X Exits the interactive mode and returns to the main
menu.
4.6 Setup Mode
--------------
This section was covered above. Use this to change the
serial port under test, the baud rate, and the type of test
to be run.
4.7 Exit Program
----------------
This is the only way to exit the Modem Doctor. This is
necessary because the interrupt tables and controllers of
your PC must be returned to their original state in order
to avoid problems after you use the Modem Doctor. Pressing
Control-C or Control-Break during the Modem doctor will
cause one of two things to happen. First, it will ignore
what you have done if it is critical that the program not be
interrupted, or second, if it is at all possible to exit
without damage, a window will open telling you that you can
control- break abort if you wish..answer yes or no. You can
Control-Break during all tests and at times from menus. If
you choose to quit, the Modem Doctor cleans things up
properly and exits to dos. Please remember this is just an
emergency way of doing an exit. Use the Exit function from
the main menu as the correct way to end the program.
The Modem Doctor Version 3.0 Documentation Page 27
Copyright (c) Hank Volpe 1989,1990
5.0 Error Messages and their Meanings
-------------------------------------
The Modem Doctor, if presented with an error, will make a
diagnosis of the problem. In most cases, this should be
enough for you to figure out what is wrong and go on from
there to correct it.
5.1 Log In errors
-----------------
ALL Available COMM ports are in use...Press to Return
-COM1 through COM8 are logged in and no new ports can be
added
COMx Not Found -A COMM port (x) was not located at the port
address specified. This is normal during auto-selection, but
not if a manual selection was entered. If a manually entered
address did not work, check your Modem owners manual to make
sure you entered it correctly. You can override and force a
port to be logged (during manual selection) if you wish as a
way to find out what is wrong with a serial port, but if you
do so, do it with caution. If the Modem Doctor determines
a port is defective, and even if you override it, you will
only be able to check the UART registers for the problem. No
other test will run.
WARNING...RESERVED port...RETRY ENTRY
- You entered a port address that is assigned to a critical
Motherboard or CPU address port. Your entry was an
error..check your modem owners manual to get the right
port.
5.2 Carrier Errors
------------------
WARNING...CARRIER FAILURE...Status Registers Displayed
above followed by;
RLS (Received Line Signal Detect indicates that a carrier
has not been received by the UART Check modem or connector
wiring
- This indicates that a "dumb" modem did not signal the UART
that it has received a carrier (or is generating one). Make
sure that your dumb modem lights the CD light during the
test (or alternately raises the RLS line to the Modem). A
modem with a Microprocessor will not display this
error.
NOTE.Carrier (RLS Line) active, it should not be..test may
not be valid (also displayed at the end of test loops)
- Check your modem to make sure that Carrier isn't forced
high. Most Modems have a CD forced High or follows Carrier
detect switch. It should be set to allow the modem to follow
a Carrier detection to insure that your modem works properly
The Modem Doctor Version 3.0 Documentation Page 28
Copyright (c) Hank Volpe 1989,1990
with all communications programs. The Modem will continue
testing after a 2 second delay.
The RLS line was Active from the UART when it should not be
-Check to see that the modem is not in the forced CD mode.
&T1 Loopback signal Sent...waiting 5 seconds to start of
test
- The Modem Doctor did not find a carrier within 15 seconds,
so it switched to the &T command set that some modems use.
If you use the &T0/&T1 driver for your modem then you will
not need the 15 second delay. Please read the section on
Modem Drivers for more information.
Modem not responding to the Analog originate test
or;
Modem not responding to the Analog Answer test
-A "AT" Instruction Set Modem did not go into the self test
mode. The Modem Doctor looks for the word "CONNECT" or the
RLS Line to go high, indicating that a Carrier was received
from the modem. A possible reason for a perfectly working
modem to generate this is if the wrong baud rate was
selected for testing. "AT" Instruction Set Modems return
identifications that can be read by the Modem Doctor. If you
suspect you selected the incorrect baud rate, go to setup
and select 300 baud and try again. If it doesn't work this
time, you might have a problem with your modem generating a
self test.
Modem Transmit Error
-The Modem Doctor attempted to send a character to the
Modem, but the status of the Transmit Holding Register
indicated that the character was never sent. This will abort
a test. Check cable wiring and that somehow the modem did
not get disconnected from the serial port or inadvertently
turned off.
Modem Queue Failure
-A character was sent to the modem, but nothing, not even
the wrong character was sent back to the Computer from the
Modem. This test is driven by interrupts, however if they
fail to happen, a brute-force method is tried one time and
if that still fails to get a character, then this error
message is displayed. Check cable wiring and again make
sure that somehow the modem did not get disconnected from
the serial port or inadvertently turned off.
CARRIER NOT DETECTED
-Some Modems in the self-test mode do not raise a carrier
(RLS) or send the word CONNECT. Instead, the MB (Modem Busy)
light blinks on the Modem. Two such modems are the Hayes
2400B and the CTS Modems. In this case, the self test
continues, but the words CARRIER NOT DETECTED are
displayed in the message window instead of CARRIER ON. This
The Modem Doctor Version 3.0 Documentation Page 29
Copyright (c) Hank Volpe 1989,1990
test is just as valid for these modems as any other as long
as you notice the light blinking on the modem. If the
Generic Modem Driver is used with &T0/&T1 modems, this will
be a normal message as it switches to the alternate test
set and continues the test.
Modem Analog Test passed without any errors in Originate and
Answer Modes - Normal results of the testing.
"You had a total of x Originate Errors and x Answer Errors
- An error was detected on character transmission by the
Modem Doctor. Use the window display to isolate the error if
you wish, or run the test again, making sure that the phone
line is disconnected.
5.3 Loopback Errors
-------------------
UART not responding using Analog Loopback Plug mode
-No characters were received over the RS-232 Loop. Make sure
you are using a proper RS-232 cable and a proper Loopback
plug
No Loopback Plug or General Failure of the Hardware
-None of the handshaking signals (RTS/CTS DTR/DSR) were
detected (or generated) by the UART. Either you have a bad
cable, a bad loopback plug or a faulty UART.
NO CTS Handshake detected. Continuing test even though
plug/modem maybe bad
-The Loopback mode looks for RTS/CTS handshaking before it
starts. If it is not there, it could be because the cable
does not have the RTS/CTS pair connected or because the
loopback plug or DCE equipment is defective. Since it
doesn't know, it gives the loop the benefit of the
doubt and starts the test. If the test runs fine from this
point on, then the RTS/CTS pair is either not wired in your
cable or your loopback plug is not wired correctly. The
reason for this display is because many high-speed modems
use the RTS/CTS pair for hardware flow-control, so its
presence is vital.
Loopback Transmit Error
-The Modem Doctor attempted to send a character to the UART,
but the status of the Transmit Holding Register indicated
that the character was never sent. This will abort a test.
If you are performing the Analog Loopback test, check cable
wiring and that somehow the modem did not get disconnected
from the serial port or inadvertently turned off. If you are
running a digital loopback test, then this indicates that
the UART is failing to send characters. If you have an 8250
or compatible UART, then this would indicate a problem. If
your UART is more or less compatible, then this message
might get displayed.
The Modem Doctor Version 3.0 Documentation Page 30
Copyright (c) Hank Volpe 1989,1990
Loopback Queue Failure
-A character was sent to the modem, but nothing, not even
the wrong character was sent back to the Computer from the
Looping source. This test is driven by interrupts, however
if they fail to happen, a brute-force method is tried one
time and if that still fails to get a character, then this
error message is displayed. If you are performing the Analog
Loopback test, check cable wiring and again make sure that
somehow the Loopback source (Plug or Modem) did not get
disconnected from the serial port or inadvertently turned
off. If you are running a digital loopback test, then this
indicates that the UART is failing to loop characters. If
you have an 8250 or compatible UART, then this would
indicate a problem. If your UART is more or less compatible,
then this message might get displayed
Analog Loopback Test passed without any errors
- Normal result of test
You had a total of x Errors
- At least one error was detected...this is the normal
result if a UART does not respond to any test.
UART not responding to the Digital Loopback test
-No characters were looped internally through the 8250 UART.
Suspect a non-compatible UART. If this test starts and then
fails, suspect the UART.
UART Registers did not set for Loop back test
-The UART Modem Control Registers did not program properly.
This should indicate a hardware failure of the UART under
all circumstances (including use with a non-compatible
UART).
UART Digital Test passed without any errors
- Normal result of test
5.4 Setup Errors
----------------
Modem Microprocessor Did Not Accept Setup Commands
-Commands were sent to setup the modem for testing, the
Modem did not acknowledge. Suspect a non-compatible modem
or a possible hardware failure.
Modem Status Register readings show that there is no status
coming back from the modem to the UART. If this is an
external modem, check" that the cable is plugged in.
-The only conditions that the UART will not have any status
is if an External Modem is off or not connected, if the
RTS/CTS and DTR/DSR lines are not active in an external
cable ,or the UART has a serious hardware problem. In the
case of a Uart problem, most likely other diagnostic error
messages will be received.
The Modem Doctor Version 3.0 Documentation Page 31
Copyright (c) Hank Volpe 1989,1990
Line Control register readings show that the word length
selected is incorrect.
-WS1 and WS0 should both be on indicating that 8 bit words
are to be used. The UART is defective or communications to
the UART are suspect.
Line Status Readings show that the Tx Holding Register THE
or the Tx Shift Register TSE is not resetting properly. UART
is suspect or connections to the UART from the computer.
-The Tx Holding Register and the TX Shift Register both
should be empty whenever the Modem Doctor Polls the register
(in between interrupts). If these are not, then the case is
99% of the time due to a bad status from the UART. A cable
could cause a problem, but its very unlikely.
Modem Control register readings show that either DTR,RTS or
OT2 signals are not set properly.
-DTR and RTS are essential for communications. OT2 is
essential for interrupts. UART is suspect or connections to
the UART from the computer
Interrupt ID register readings show that an interrupt is
pending when none should be. UART is suspect or connections
to the UART from the computer.
Interrupt Enable register readings show that ERI Enable
Receiver ints is not set properly. UART is suspect or
connections to the UART from the computer.
8259 Interrupt Controller has not responded to setting the
IRQ(x) line. This problem is on the system board of your
computer. Run your computer diagnostics program to locate
the error. -This error may be displayed if you also try to
log-in a defective Comm port, or if the 8259 failed to set
the correct interrupt line. IRQ4 = COM1/3, IRQ3 = COM2/4,
IRQ5 = COM7/8, IRQ 7 = COM5/6. If this error was displayed
when logging in a defective Comm port, yet the controller
responds properly on correctly operating Comm ports, then
the error report can be safely ignored.
I cant find a COMM port
-If Dos does not Log in Comm 1 or Comm 2 and if no port is
Auto-Detected, then the Modem Doctor Aborts for there is no
reason to run the program.
WARNING...This COMM port is MODEM STATUS/CONTROL REGISTER IS
DEFECTIVE
-The Modem status register is one of the registers tested
during auto-login detection. If it doesn't respond properly,
the UART is probably defective and this message is
displayed. The Modem Control register is also checked.
Failure of either of these usually indicates your Uart is
defective.
The Modem Doctor Version 3.0 Documentation Page 32
Copyright (c) Hank Volpe 1989,1990
Section 6. Special Modes and Information
----------------------------------------
The Modem Doctor supports a wide range of "AT" instruction
set modems. There are however "supersets" of instructions
that manufacturers have used to enhance the capability of
their modems. Although there is some structure in this
area, not all commands intermix between different brands and
lines of modems. This situation is analogous to PC computer
printers, and it calls for a similar approach. The Modem
Doctor now supports the use of "Modem Drivers" to meet these
special needs. Additionally, due to the increase in
computers using the ISA bus, there are more interrupt lines
free to be used by modem manufacturers. For test purposes,
you can use IRQ3,4,5,7 for your hardware testing. Using the
special /S switch, you can send initialization codes to your
modem from a batch file or other command-line need to setup
the modem for use. Finally, to add some flexibility to the
Modem Doctor's diagnostics, some special "Hot-keys" have
been added. These have been discussed above in an
operational sense, however in this section you will get some
ideas of how these can help you speed up testing and test
defective or non-compatible hardware.
6.1 Using Modem Drivers
-----------------------
Most Modem's today are built on the original "AT"
instruction set that was developed by Hayes Micromodems in
their 1200B series. This driver, named the Generic Driver in
the Modem Doctor, is used exclusively if the modem returns
an ID indicating it is a 300,1200 or 2400 bps modem. Also,
if the modem does not return an ID, this Generic Driver is
used. The Generic Driver can be used to test nearly all
modems, however there are some 2400 bps modems that were
built using the command structure that Hayes Micromodems put
into their 2400B line. These modems used an "&" for some
modem setup and command functions. The Modem Doctor has a
driver for these modems called the "&T0/&T1" driver. Using
this driver, the Modem Doctor can perform a simulated
carrier test. During your testing of this type of modem, you
will notice the MB (Modem Busy) light flashing on your
external modem. This driver (and all others) is user
selectable, however the Modem Doctor will automatically
switch to it when performing the carrier tests if the Modem
was detected to be a 2400 bps modem. The last driver
currently supported is for US Robotics Courier HST and HST
Dual/Standard V.32 Modems. The Modem Doctor recognizes these
modems upon initial testing and sets up its test parameters
a certain way to compensate for their Carrier self test
limitations.
The Modem Doctor Version 3.0 Documentation Page 33
Copyright (c) Hank Volpe 1989,1990
Because of the trellis-encoded Async/modulation of the USR
HST Mode, the maximum Carrier test Baud rate is 2400 bps
(see the USR Manual for this info). To work around this, the
Modem Doctor Programs these modems to use a fixed DTE/DCE
Rate with the &B1 Parameter, allowing communications to and
from the modem at speeds up to 19200 bps. When working in
the V.32 mode however, the Carrier test (and all loopback
tests ) can be performed at 9600 since the modulation is
symmetrical again. Also when the selected baud rate is
higher than 2400 bps, the MNP Protocol switch is set to &M0,
otherwise if there was an error, the Modem would try to
correct it instead of passing the error on to the Modem
Doctor. None of these changes is saved to the non-volatile
ROM, so you should not experience a problem. However, the
V.32 and Dual Standard Modems might experience a problem if
register S13 is not set to 1. This is the default from the
factory and insures that the modem will be reset when the
DTR line is dropped. If you are experiencing a problem, use
the interactive mode and type S13=001. This change is not
permanent. If you are using a USR Dual Standard Modem, then
the Modem Doctor will test whatever mode is active via the B
switch. If the current Modem setting is B0, then the V.32
mode will be tested, if B1 is set, then the HST mode will be
tested. You can change this setting to whatever you
wish by using the Interactive mode, type ATZ, then type ATB0
&W or ATB1 &W. This has to be written to the firmware in
order to stay valid throughout all the testing, but the ATZ
command before a save will always recall your settings,
insuring you have only changed the one parameter. Please
note, this is included for advanced users and is one of the
reasons for the interactive mode. It is not necessary for
you to do this to test your modem unless you wish to. For
more information, see the section regarding "Quirks".
As mentioned above, all of the Modem Drivers are self-
selecting, but can be user-selected. The status line of your
screen will display the current Port assignment, the current
Baud rate, the status of the Microprocessor, and the current
Modem Driver being used. Select carrier test from the Main
menu and move the bar to "Select Modem Commands". You will
be given a choice of the available drivers. After you
select, the status line will be updated, and you can either
start the test or return to the main menu. The reason for
Modem Drivers is to allow more individualized testing of a
particular type of modem, and to allow for more modems to
added to the list of specially supported modems. Although
not supported in version 3.0, the program will in the future
be able to access external modem drivers that can be
provided to a customer for special testing or to enhance the
abilities of the Modem Doctor. If you wish to have a custom
interface written, please contact us for pricing and
appropriate information that we will need to do this for
you.
The Modem Doctor Version 3.0 Documentation Page 34
Copyright (c) Hank Volpe 1989,1990
6.2 Using the Command Line Mode switch /S
-----------------------------------------
There can be special occasions where you need to initialize
and test a modem before another program can be run. The
Modem Doctor now supports a method to do this. Using the
command line switch /S, you can instruct the Modem Doctor to
"wake-up" a Modem and send an initialization string to it.
Although similar to our product Comset, it offers some
additional flexibility but does not allow the serial port
only setup that Comset does. To use this special mode, you
need to have a companion file named MDR.DAT that you create
with any ASCII text editor that follows this format;
All information must start on the first space on each line
and can consist of up to 3 lines. Line 1 and Line 2 are
required.
Line 1 = Port Number 1 through 8 and an optional Port
address in [] ( For settings greater than Port 4, this
address is required).
Line 2 = the Baud Rate you wish to use (300-38400 or 3-384
are acceptable)
Line 3 = the initialization string you wish to send. This
string must start with AT and can be up to 80 characters
long. If no string is included in the file, or if it does
not begin with the letters AT, then ATZ is automatically
sent to the modem.
Example..to setup Port 2 to 19200 and set S7 to 255;
Make a file called MDR.DAT that looks like this;
2 [2F8]<--note for Port 1-4 unless it is non-standard [2F8]
is not needed
192
AT S7= 255
Next, start the Modem Doctor by typing MDR /S
As long as the MDR.DAT file is in the current working
directory, these commands will be sent. If not, you will get
an error message stating that MDR.DAT could not be found.
Why not have the Modem Doctor search all directories for the
file? Well, the reason is so that you can put MDR.EXE in a
Dos path but have individualized setup MDR.DAT files in
different subdirectories for different programming needs.
Instead of constantly changing the file, make different ones
and call MDR.EXE. It will only use the MDR.DAT file in the
current working directory.
After the initialization string is sent, the Modem Doctor
will wait up to 10 seconds for the word "OK" to return from
the modem. If it does not, you will get a message saying the
modem failed to setup. In either case, whatever your modem
sent to the Modem Doctor will be displayed. If you see the
The Modem Doctor Version 3.0 Documentation Page 35
Copyright (c) Hank Volpe 1989,1990
word "ERROR", that was sent from the modem, it probably
means that your initialization string was not correct. No
message returning could indicate a problem with the modem,
or an invalid baud rate. When it finishes executing, the
Modem Doctor returns an errorlevel to the calling program.
An errorlevel of 0 is normal, an errorlevel of 99 indicates
a failure. You can use these errorlevels to control batch
processes if you wish to.
Also, this mode of the Modem Doctor uses bios screen writes,
so all of the information displayed can be redirected to a
printer, a file, or whatever other DOS device you wish.
Example...to send the output of this test to a file called
Test.txt...
MDR /S > TEST.TXT or MDR /S >> TEST.TXT (if you wish to
append an existing Test.txt file.
If the Modem Doctor setup was successful, the modem's DTR
and RTS lines stay active, if not, they are dropped. If you
need more specialized command-line modes of operation, you
might consider Comset. Comset allows Serial Ports and Modems
to be setup at various rates and under various conditions.
Registered Modem Doctor users get a 15% discount! You can
find Comset on most BBS's as COMSET6.ZIP.
6.3 Using the Hot-Keys
----------------------
Hot-Keys are combinations of the ALT key plus a letter. The
Modem Doctor adds several of these Hot-keys to make it
easier to test modems at different baud rates and to
circumvent some of the error checking that the program
performs under normal circumstances.
ALT-B Change Baud rate - If you are testing a system that
you suspect has a problem, it is best to use the setup mode
when changing the baud rate. The Setup mode will test all
the registers, and the modem microprocessor (if selected)
and assure you that all the hardware is communicating
properly at each baud rate. However, if you feel a system is
running fine, using the ALT-B from the main menu can save
time when running tests at different baud rates. Press ALT-B
and select the baud rate (taking care not to select a rate
higher that what your modem is rated for if you are doing
modem tests). ALT-B works from the main menu, and from
inside the Manual interactive mode.
ALT-C Clear Screen - This key is only active inside of the
Manual interactive mode and is used to clear the text window
of any characters.
The Modem Doctor Version 3.0 Documentation Page 36
Copyright (c) Hank Volpe 1989,1990
ALT-F Force Microprocessor on-line - The Modem Doctor has
many tests built-in to verify the working condition of a
microprocessor-based modem and will not allow a modem to be
tested in the "AT" instruction set mode if it has not
properly addressed and setup a modem microprocessor. Using
the ALT-F combination forces the Modem Doctor to perform
tests as if it had properly setup a modem. This feature
should be used with care, however its primary benefit is to
help you test a malfunctioning modem to see exactly what
commands it will respond to. Pressing ALT-F also updates the
status bar to indicate that the modem microprocessor is on-
line (which may or may not be the case after this command
was issued).
ALT-R Register Display - This is only active inside of the
Manual interactive mode and is used to display the status of
all Uart registers on the screen for diagnostic purposes.
ALT-X Exit Mode - This is only active inside of the Manual
interactive mode and is used to exit this mode.
6.4 Logging in Defective Ports
------------------------------
If a serial port Uart is defective, the Modem Doctor will
refuse to log it in for testing. This is necessary because
there is no way for it to know what ports are defective and
what are non-existent. However in Version 3.0, you can now
log-in a defective chip for testing. The procedure to do so
is explained above under Manual Login. The reason for doing
so however might not have been apparent. If any register of
a serial port is defective, it might not function properly.
Logging in this defective port will give you the full
benefit of the Uart and Serial port diagnostics. Error
messages will be displayed, in most cases there will be
multiple error messages. There are two possible causes of a
defective port; the Uart chip and the Serial Port address
system. If it is a chip, simply replacing the chip fixes the
problem. If it is a serial port instead, then the same
problem will repeat. How do you approach this? Well for
starters, check that the strapping on your serial port board
matches the correct COMM port assignment (ie strapped for
COM1 for COM1..etc). Next, if there is user selectable IRQ
assignments, make sure it again matches the COMM port
assignment (IRQ4 for COM1/3, IRQ3 for COM2/4, IRQ5 for
COM7/8, IRQ7 for COM6/7). If all this is set properly, then
you can suspect the chip, but also the Serial Port hardware
that gates the address of the chip to the computer. Finally,
if you get warnings about status, but the chip logs in, then
you might just have a bad cable from the computer to the
modem (NOTE: The Modem Doctor does not consider this an
error but simply displays a warning and allows the Uart to
be logged-in for use).
The Modem Doctor Version 3.0 Documentation Page 37
Copyright (c) Hank Volpe 1989,1990
6.5 What tests cannot Do
------------------------
Although I tried to be extremely thorough in my tests, there
are somethings that tests just cannot do or pinpoint. If you
are having problems with excessive line-noise, you might
have a bad connection between your modem and your telephone
wiring in the house. Another possibility, although remote,
is that your modem does not offer the correct input
impedance to the telephone line. This can cause poor
connections. The problem is with the electronic design of
the modem, and again, it is more prevalent in inexpensive
modems. Also, tests cannot check that the communications
program you are using is set up correctly. At times,
installing a communications package can be very challenging
for a novice user. Tests also cannot check the wiring in
your serial Cable. The Modem Doctor will tell you if a
handshaking pair is missing, but it cant tell you why. It
could be because the UART is bad, but more than likely,
your RS-232 Cable doesn't carry all of the handshaking
signals to or from the external modem or serial device. This
can be important if you are using a high-speed modem. Most
High-speed modems will drop the CTS line when their
communication buffers are full. Previous Modems ignored
the RTS/CTS signals and instead used the DTR/DCE pair. What
this means is that if you buy a new modem, it might not work
with the older-cable (yet at the same time the older modem
will work..which might lead you to believe that you have a
defective modem).
6.6 Quirks with Some Modems
---------------------------
Carrier tests - Some Modems have two "AT" instruction sets,
usually referred to as Compatible and Enhanced. If your
modem does not perform a carrier test at speeds below 4800,
then this is usually the case. Some modems provide a dip-
switch or a toggle switch to select either mode. Setting
your modem to the Standard Compatible Mode should get rid
of your problems below 4800 bps. Also, make sure you select
the Generic Compatible Modem Driver unless you are sure your
modem matches the modem's that have special drivers written
especially for their use. At speeds above 4800 bps, the
Modem Doctor is only compatible with USR V.32, Dual
Standards (V.32 and HST) and HST brand of modems. If you
wish to test another brand of modem that is not compatible,
simply turn off any modem-hardware error correcting using
the Manual mode and following the information in your modem
users manual. Then select the Generic Modem Driver and you
should be able to test your modem properly. Finally, if
only one of the tests (Originate or Answer) runs and NO
CARRIER is displayed for the other, the problem lies with
the Enhanced Command settings of your modem. Hayes Modems
use &T1 through &T8 commands for their 2400 and also have
The Modem Doctor Version 3.0 Documentation Page 38
Copyright (c) Hank Volpe 1989,1990
other special switches. The &T0 command set is tried by this
version of the Modem Doctor automatically, however there is
no compensation for any other type of modems that use
non-standard commands. Again for the sake of compatibility
with the widest range of modems at speeds below 4800, this
cannot be corrected for in this version. Considering the
vast numbers of "AT" compatible modems in the
marketplace, these two exceptions are minor and will not
affect most users. Finally, users of 8250 compatible UARTS
that do not support the Digital (Chip) Loopback will get an
error. This should be of no concern. However if the test
runs for a while, then fails, it could indicate a
problem with your UART. This is explained in the pull-down
window in the program. The Modem Doctor has been tested on
about 25 Modems from Major Manufacturers and on a variety of
Clones and Compatibles (plus the "Real Thing"). It is
possible that a certain combination of hardware still might
give problems, however if you are a registered user, I will
find a way to make it work.
Section 7. Benefits of Registration
------------------------------------
Thank you for your registration. The Current Registered
Version # of the Modem Doctor is 3.0R. All Registered Users
are entitled to free Maintenance updates and these will be
reflected by changes in the decimal fraction number..ie
3.01, 3.02. Also, if a new super-duper version comes out
(4.X or 5.X), all registered users will be able to update
for only $5 (plus $ 2 for shipping,handling plus tax where
applicable). If you have trouble with the Modem Doctor, or
questions, feel free to call or write. When doing either you
will need to have the Version Number, your serial number,
and in some cases the Module Identification Number. The
Version number is displayed when you first start the program
along with the serial Number. The Module Identification
Numbers can be displayed at any time from the main menu
after you pass the initial setup mode. Simply type a # sign,
and all of the modules that make up the Modem Doctor will
display their version numbers on the screen. Right now, all
Modules have identical version numbers from program to
program, but in the future, there could be custom modules
for registered users, so in this case the Module ID could
become important. You can reach us with your questions at
716-694-7484 or write to ;
Hank Volpe
108 Broadmoor Drive
Tonawanda NY 14150
Thanks again for registering the Modem Doctor.
The Modem Doctor Version 3.0 Documentation Page 39
Copyright (c) Hank Volpe 1989,1990
Notes - [+] References to USR /Courier/Dual Standard/HST
Copyrighted by US Robotics
[++] References to AT Instruction Set ,Smartmodem,Hayes
Copyrighted by Hayes Inc.
References to MNP refer to An error free protocol
Copyrighted by Microcom Inc.
Disclaimer - It is not the intent of the Author to
recommend any brand of modem over another nor to infringe on
the Copyrights of the Manufacturers by mentioning their
products. A modem fits a need, and whatever one works for
you is the one you should have. As time goes on, more
modems will be added to the list of "special enhanced "
tests. The modems mentioned are done so only because of the
popularity they enjoy and for no other reason.
The Modem Doctor Version 3.0 Documentation Page 40
Copyright (c) Hank Volpe 1989,1990
Modem Doctor History
Ver 3.0 - New tests added for 16450/16550/16550AN Uarts.
Improved Control-Abort handling, Regs command now
performs a full diagnostic call when activated.
Hot-Keys added (Force Micro, Baud Rate Select).
Modem Driver software added to program, Status Bar
added to program. Support for IRQ 3,4,5,7 added
via COM1 through COM8 log-ins. Speed increased to
38.4KB. /S Command line option added for setup of
a modem including batch file errorlevel support.
Escape key functionality added to Carrier Tests
and the loopback tests.
Ver 2.2 - Corrects a bug in Ver 2.1 Communication routines
that caused some modems to lock-out because they
were waiting for two carriage returns to begin.
Also it added 4 diagnostic Uart tests
Ver 2.1 - This version was a Beta test. A Beta tester
accidentally uploaded this to several boards.
Please remove all Ver 2.1S software that you may
find.
Ver 2.0 - This version also was a Beta test with support
for COM1-2 and 2400 bps maximum
Ver 1.0 - First test version