
                      A Comparison of High Speed Modems
                   Compatibility/Features/Differences/Prices

                 Including: HST, V.32, V.32bis, V.42, V.42bis

                By Mike Ehlert, SysOp: PACIFIC COAST MICRO BBS
                        USR HST/V.32bis (805) 494-9386
                        USR HST 14.4k   (805) 497-3456
                        CC Speedmodem   (805) 496-7320
                             FidoNet 1:102/1001

                Edited by Jeff Rigby for the Atari Forum
------------------------------------------------------------------------

                              A High Speed Modem
                              ==================

Are you thinking of going to a High speed modem?

2400 bps can be very slow for transferring large files.
Modems advertised as 4800 are really only 2400 with data compression
such as MNP-5 or even just software data compression. There are now
some new 2400 BPS modems with V.42bis, which claim 9600 bps Thruput.
Don't be fooled. A 2400 bps modem with error correction will NOT be
significantly faster when transferring compressed files such as ZIPs.
An actual 9600 BPS or faster modem will make a tremendous difference in
your transfer time. Most 9600 BPS users never want to go back to 2400.
There is a lot of confusion and mis-information about 9600 bps and 
faster Modems. I wrote this to help clarify and point out the 
differences between the different modems available IBM compatible 
machines.

                           
-----------------------------------------------------------------------

                               The CCITT
                               =========        

The International Consultive Committee for Telegraph and Telephone 
(CCITT) set the V.32, V.32bis Standards in 9600 bps communications.
They have also set the standards of 1200 and 2400 bps in Europe which 
differ from the "BELL" standard in the US. 

Unfortunately the V.32 standard was very expensive to implement for the 
modem manufacturers and several non standard 9600 protocols were 
developed and implemented since the release of the V.32 standard in 
1984.  The HST has already become the industry standard in the IBM BBS 
world.  

Since the release of new LSIC (Large Scale Integrated Circuits) that 
make the V.32 9600 baud modems very cost effective and the fact that 
the V.32 CCITT standard is a Public Domain (no license or royalty), 
there is more price competition going on with these than with the HST, 
which currently has no true competition.

------------------------------------------------------------------------

                        Half Duplex Vs. Full Duplex
                        ===========================

Half Duplex is When Data is Transmitted in one Direction at a time.
Full Duplex is both directions at once. 2400 BPS modems are Full Duplex
The HST Modem uses an improved form of Half Duplex, in which one 
direction is transferring at high speed while the other direction is 
sending ACK/NAK signals at a slower speed. A similar method is used on 
the Speedmodem.

V.32 modems use Full duplex, which in most cases does not improve
performance when used on a BBS. There is one way to take full advantage
of a Full Duplex Modem: By using a protocol called Bimodem to upload and
Download at the same time at 9600 bps in each direction! Unfortunately
Bimodem has not become very popular. Most BBS's and users still use one
direction transfer protocols such as Zmodem or YModem-G.

------------------------------------------------------------------------

                        What is MNP, HST, V.32, V.42?
                        =============================

                                     MNP
                                        
MNP (Microcom Networking Protocol) levels 1-4 are methods of error 
correction in which the two modems connected verify the integrity of the
data transmitted. Error correction is required for several streaming
protocols such as Ymodem-G in which the protocol sends a constant stream
 of data and lets the modems do the error correction. This requires a 
clean, noise free line as streaming protocols will abort if line noise 
interferes too much. These MNP Levels are used in almost all High Speed
Modems Made today, But Just because two modems both have MNP it does 
not ensure that they will both talk to each other at over 2400 baud.

MNP Level 5 is for data compression. Since All BBS's have their files 
archived in ZIP, LZH, GIF or some such compressed format (try to ZIP a 
LZH file), MNP5 can actually increase the overhead by attempting to 
compress the file further. Therefore BBS's leave MNP5 turned off, and 
so should the BBS callers.

------------------------------------------------------------------------

                                  HST

HST stands for "High Speed Technology" - a method of communicating at
high speeds which was developed by US Robotics in 1984. The original 
HST modems were 9600 BPS by using a 9600 bps channel in one direction 
and a 300 (later 450) bps "back channel" in the other to send ACK/NAK 
signals for confirmation of data - a half duplex mode - often referred 
to as "ping-ponging". In 1989 USR improved the HST to run at 14400 bps 
by further optimizing their proprietary method. All HST's sold now 
include the 14400 bps speed as well as the original 9600 bps mode. 
Because the HST 14400 bps is the raw speed, It allows the HST to 
transfer pre compressed files such as ZIPs at faster speeds than any 
other 9600 bps modem: over 1700 Characters per second (cps).

The HST has become the "BBS-Standard" in high-Speed modems. More BBS's 
use the HST than any other type of modem, including the V.32.

As of January 1st 1991 all HST modems also include the V.42/V.42bis 
error correction and data compression (not to be confused with V.32).

The HST's can also be upgraded to the HST "Dual Standard" allowing it 
to also be V.32 compatible. The price is significant for this upgrade 
however, and in very few cases is any speed gained.  

V.32bis modems from USRobotics use an all new circuit board. Previous
models *CANNOT BE* upgraded to V.32bis. There *IS* a trade-in/trade-up
program, but it's a rip-off at $575.00 plus your old modem in trade!

------------------------------------------------------------------------

                                   V.32 

V.32 is a 9600 Baud standard that was established by the CCITT back in
1984. V.32 is full duplex (9600 bps in both directions at once).
Normally this would be impossible, but using a technique called "echo
cancellation", one modem can filter its own tones from the phone line,
enabling it to pick out the signals from the other modem. However, echo
cancellation requires that high speed modems include built-in digital
signal processor (DSP) chips, which is the main reason V.32 and V.32bis
costs so much. V.32 also includes a fallback to 4800, if line noise 
becomes a problem at 9600. The V.32 standard also provides an optional 
error-reduction scheme, called "trellis-coded" modulation (TCM). TCM 
allows 9600 modems to check for transmission errors with a redundancy 
bit, which results in fewer errors on noisy lines. Most V.32's include 
this option, but some do not.

------------------------------------------------------------------------

                                 V.32bis

It was first realized in 1989 that it is feasible to push V.32 up to
14400 bps, the same speed as the HST now runs. This requires even
better echo cancellation and an overall improvement in receiver quality,
so it is also more costly to produce than the V.32. V.32bis has not yet
officially been finalized by the CCITT, but as of January 1st US 
Robotics has started shipping a new version of their Dual Standard 
Modem which includes V.32bis in an early but functional form. USR plans 
to update their DS ROMS when the CCITT actually release the completed 
V.32bis specification, scheduled for mid 1991. It's expected that other 
Modem manufacturers will not be able to offer the V.32bis technology 
until the 4th quarter of 1991.

------------------------------------------------------------------------

                                   V.42

V.42 has nothing to do with actual modem speed, but how the error 
correction and data compression schemes interface. When the CCITT 
approved V.42 in 1988, they decided to include two different error 
correction and data compression schemes. The first one is MNP,(short 
for Microcom Networking Protocol) MNP classes 2, 3, & 4 handle error 
correction. Note that MNP-5 was not included in the V.42 standard 
because it is only used for data compression. MNP was made an official 
standard due to the large number of modems that currently use it. 

The Second method is the preferred method, known as LAP-M (Link Access 
Procedure for Modems with only MNP is called "V.42 Compatible" and one 
with LAP-M its known as "V.42 Compliant". If a V.42 Compliant connected 
to a V.42 compatible, it would first try to Handshake with LAP-M, and 
after it realized that the other modem is not Compliant, it would try 
the MNP Method, and they connect.

Most V.32 modems are fully V.42 compliant, but they do NOT have to be,
according to CCITT guidelines. So when purchasing a V.32 modem make sure
that it is also fully V.42 compliant, not just V.42 compatible.

There are now some 2400 baud modems which are also V.42bis compliant,
so since the LAP-M gives 4:1 data compression they are advertised as
"9600 throughput", which really can be misleading and confusing.
Don't be fooled by any throughput claims. The raw speed is what matters
when transferring compressed files such as ZIPs.

-----------------------------------------------------------------------

                                 V.42bis

V.42bis is a new CCITT standard for data compression techniques, which
was approved in late 1989. To Support V.42bis, a modem MUST support both
LAP-M and MNP-5, unlike the Standard V.42 in which LAP-M is only an 
option.  V.42 provides a maximum data compression of 4:1, giving a 
9600 bps modem a throughput of up to 38400 bps. MNP only offers 2:1 
Compression.

As I said above, data compression is not very useful when transferring
pre-compressed files, (such as ZIPs) from BBS's. V.42bis has a special
ability, (unlike MNP-5) to determine if the file can be compressed 
further or not before making the an attempt to do so. Therefore v.42bis 
will not slow down a ZIP transfer, and may even speed it up a little 
bit.

Since V.42bis is implemented in firmware, many V.42 compliant modems can
be upgraded to V.42bis with a new ROM chip.

------------------------------------------------------------------------

                               Speedmodem

A less expensive method of 9600 bps communication can be achieved 
without using the CCITTs method of "echo cancellation", so that a 
digital signal processor is not needed, making the cost much less 
expensive. This method is used on the Compucom Speedmodems. The 
Speedmodem uses Dynamic Impedance Stabilization (DIS) to increase the 
reliability of the telephone interfaces signal-to-noise ratio of the 
telephone line by increasing the clarity and power of the signal, and 
automatically compensating for impedance variations on the phone line. 
This reduces the probability of line noise, allowing the Protocols to 
transfer files with less overhead. It also has a faster fallback rate 
of 7200 bps if too much line noise exists for 9600 bps communications. 
This makes the Speedmodem stand up to worse line noise conditions at 
a faster rate than V.32 can handle.

The Speedmodem is available in two versions. the "Speedmodem-Champ", 
and also the "Speedmodem-Combo". The Combo is the same modem with the 
addition of a 9600 bps Fax, and a Voice-Mail system as well. The Combo
comes with BitFAX by Bitcom, and supports any other 3rd party FAX 
software which uses the standard CCITT AT-FAX command set. The Voice-
Mail software is currently still under development, which will allow 
your computer work similar to an answering machine, using the hard 
disk to store voice messages, and allowing several different message 
areas or "Mail-Boxes" to be accessed from a touch tone telephone. 

A Data Compression called CSP (CompuCom Speed Protocol) is used to yield 
a compression of up to 4:1, giving a throughput of up to 38400 bps. 
This however, like MNP5 will not be effective when transferring 
compressed files from BBS's, such as ZIP files.

DIS and CPS are proprietary methods owned by CompuCom, Sunnyvale, CA.
Because this modem is very inexpensive more people can afford to buy 
it, which could cause it to gain popularity quickly. It is still a new 
product, but hundreds of BBS's are showing support for it.

The one drawback to this modem is that it will connect to HST and V.32
modems only at 2400 bps. It will connect to other Speedmodems at 9600 
bps, and the Combo version will connect to Fax machines at 4800 or 9600 
bps.

------------------------------------------------------------------------
                               What Next?

By mid 1991 the V.32bis standard will be finalized, and by the years 
end several 14400 Bps full duplex modems will be on the market. There 
is already talk of the CCITT releasing another standard, V.32ter in 
1992, which will be for 19200 bps. Since these modems are expected to 
cost considerably more than the V.32s currently on the market, they 
will be out of the price range of most BBS users.

-----------------------------------------------------------------------


                           WHAT TO LOOK FOR

THROUGHPUT:
==========

You'll see ads claiming that you can attain 19200 bps or 38400 bps
with a 9600 bps modem - this is true only if you are using MNP5 or 
other forms of data compression on uncompressed data or text files. 
Any 9600 bps modem using compression can transfer at that effective 
rate. But for BBS use, where files are already compressed (such as 
ZIPs, LZHs, GIFs) MNP5 will actually slow down throughput by 
attempting to compress a file that is already compressed. Generally 
when using a modem for BBS transfers, its the RAW speed of the Modem 
and not the throughput which is important.

Figures of around 1700 cps by the HST modems are attained through 
proprietary methods not yet available on other modems.


CONFIGURABILITY:
================
In High Speed Modems, there is a lot more to configure than on a 
2400 bps modem. Be sure your modem comes with NVRAM (Non-volatile 
Random Access Memory) that can store your modem configuration, making 
long init strings unnecessary. Also many modems have dip 
switches to set the default configuration, which also  simplifies
things.  

Your Hardware
=============

Can your computer hardware support the speedy new modems at their 
highest speed?  Can the BBS you are connected to support these speeds?
Generally NO.  Most serial ports/Hard Disk combinations can't support 
over 19,200 baud.  Large RS-232 buffers can help and some effort to 
match the hard disk performance to the size of the RS-232 buffer would 
be advisable.  HD caches also help on slower PC systems.  Multi-line 
BBS systems suffer from time/job splicing further reducing their speed.

Most Modem manufacturers are recommending that MNP5 and V.42bis not be
used (configured off in NVRAM) in BBS systems.  There are two reasons 
for this, only one is mentioned by the Manufacturer.  The first is that 
ZIP compressed files don't show any decrease in transfer time since the 
V.42bis (4:1) compression can't further compress an already compressed 
file. The second is that the majority of the BBS system hardware can't 
support a sustained 38,400 baud.

Why offer Modems with transfer speeds over 19,200?  High end computer
systems (UNIX and mainframe systems) can and usually do use speeds 
over 19,200.     

PC software usually has an option for 38,400 baud even though most PC's 
can't sustain those RS-232 rates.  There are HIGH end PC RS-232 boards
that can easily handle those speeds especially the EISA designed boards. 

The Atari ST uses a 68901 for it's serial communication.  The Midi port 
uses a combination of 68901 and a 6850.  Several years ago I was 
involved in a project to use the MIDI port as a LAN and we needed to 
find the maximum transfer rate of the Midi port.  Turns out that it's
speed is limited by the interrupt priority determined by the Glue chip 
and figures out at 31,500 bits/sec (baud).  The serial port has the 
the same limitation so no RS-232 speed above 19,200 is available in the 
Control panel or in Commercial Software.  (The next RS-232 speed above 
19,200 would be 38,400 baud and the max RS-232 (hardware rate) is 
somewhere below 31,000 baud)

The Atari TT for compatibility reasons only supports 19,200 in it's 
control panel but one RS-232 port can transfer at 91,000 baud and the 
others are surely capable of 38,400. So we should see commercial 
software supporting those higher speeds by 92.
 

If Considering a USRobotics Modem
=================================
You only need to worry about whether you want the HST 
(which can be upgraded later to V.32), or the new Dual Standard
which is HST, V.32 and now V.32bis as well.

If Considering a V.32
========================================
Some questions to ask:

Can you afford the USR "DS" instead?
Is it V.42 compatible, V.42 compliant, or V.42bis? compliant
If its not V.42bis or compliant, can it be upgraded?
Do Local/National BBS's support it?
What is the warranty? 5 years?

If Considering a Fax/Modem
==============================
some questions to ask:

Does it both send and receive Fax (some are SEND only)
Does it support 3rd party FAX software?
What's the Fax transfer speed Is it 4800 or 9600 bps?
What's the modem DATA speed?
Does it support MNP, V.42, V.42bis?
Does it support other compression?
Do Local/National BBS's support it?
What is the Warranty? 5 Years?

---------------------------------------------------------------------------

                    Modem Compatibility Listing:
                    ============================


These modems will usually be downward compatible with 2400 bps and 
slower modems, Which means they are also CITT V.22bis and Bell 103/212A 
compatible.  Most have an auto-fallback mode that will detect the 
highest negotiable bps rate. If the modem is V.42 capable, it will fall 
back to MNP if the other modem is not LAP-M  capable, but is MNP 
capable. Modems supporting MNP will connect with data compression/error 
correction with other MNP modems at the highest bps rate common between 
the two. The speeds listed here are the actual Raw speed, and not the 
possible throughput that can be achieved using data compression.
 
Listed in alphabetical order by brand name - 

Generic V.32 only
   Made by a number of companies using the CCITT method of communicating at
   9600 bps.
   These are expected to become outdated as V.42 is added to most V.32 
   modems - Talks to other brand V.32 modems at 9600 bps.

Generic V.42 Only
  If a modem is V.42 or V.42bis only, and not V.32, then it is only a
  2400 bps modem, and can only talk to other V.42 modems at 2400 bps
  (with supposed 9600 throughput using data compression)
  This is not considered a 9600 bps modem and should be avoided.
- Talks to other brand V.42 modems at 2400 bps with LAP-M.

Generic V.32 with V.42 (and/or V.42bis)
   These modems follow CCITT V.32 standard for communicating at 9600 bps,
   and also have V.42 data compression and error correction.
 - Talks to other brand V.32 modems at 9600 bps
 - Talks to other modems with the V.42 option at top negotiable rate.

(Some Generic Brands include: Anderson Jacobson, Cardinal, 
Codex, Computer Peripherals, Digicom, E-Tech, Farallon, Fastcomm, 
General Datacom, Intel, Magic, Mastercom, Microcom, Multi-tech, NEC, 
Practical Peripherals, Prometheus, Radcal Vadic, Shiva, Telebit, 
Telenetics, USD, and many others just appearing. Some of these offer 
LAP-M and V.42bis, and some do not.)


 Hayes V-Series:
   The early Hayes V-Series uses a proprietary method of communicating 
   at 9600 bps.
 - Talks other Hayes V-Series modems at 9600 bps.

 Hayes V-Series V.42:
   The Hayes V-Series V.42 uses the proprietary method of communicating 
   at 9600 Baud but will incorporate the V.42 data compression and 
   error checking 
   - Talks to other V.42 modems at 2400 with error correction/compression.
   Talks to other MNP modems at 2400 using error correction/compression.
   Talks to other Hayes V-Series at 9600 bps.

 Hayes ULTRA:
   Uses CCITT V.32 and method for communicating at 9600 bps.
   Has MNP5 abilities.
   Has LAP-M abilities
 - Talks to Other V.32 modems at 9600 bps
   Talks to other modems with the V.42 option at top negotiable rate.
   Talks to other Hayes V-Series at 9600 bps

 Telebit Trailblazer:
   Uses proprietary PEP method of communicating at 9600 bps.
   Has MNP5 abilities.
 - Talks to other Telebit Trailblazers at 9600 bps.
   Talks to other MNP modems at 2400 baud with error correction/
   compression  

 USR Courier V.32:
   Uses CCITT V.32 method of communicating at 9600 bps.
   offers MNP5 abilities.
 - Talks to Other V.32 modems at 9600 bps.
   Talks to other modems with the V.42 option at top negotiable rate.
  
 USR Courier HST: (old version)
   Uses the USR proprietary HST method of communicating at 9600 Baud.
   Has MNP5 abilities.
 - Talks to HST type modems at 9600 bps.

 USR Courier HST: (current 14400 bps version)
   Uses the USR proprietary HST method of communicating at 9600 and 14400 bps.
   Has MNP5 abilities.
 - Talks to HST DS's at 14400 bps
   Talks to HST (current) at 14400 bps
   Talks to old 9600 HST's at 9600 bps.

 USR Courier HST DS:
   The Dual Standard incorporates both the proprietary HST method of
   communicating at 9600 and 14400 bps,  and the CCITT V.32 method of
   communicating at 9600 bps. 
   (and V.32bis 14400 bps on units made after 1/1/1991)
   Has MNP5 abilities.
 - Talks to Other V.32 modems at 9600 Bps. 
   (V.32bis models will talk to other V.32bis modems 14400 bps)
   Talks to other DS's at 14400 bps
   Talks to 14400 HST's at 14400 bps
   Talks to old 9600 HST's at 9600 bps.

COMPUcom Speedmodem
    Uses the Proprietary DIS method of communicating at 9600 bps.
    Has 7200 and 4800 bps Fallback
    (Speedmodem-Combo Has CCITT FAX V.27ter & V.29)
    Has MNP5 abilities.
    Has CSP abilities. 
    (Speedmodem-Combo) Talks to Group III Faxs at 9600.
   -Talks to other Speedmodems at 9600 bps.
    Talks to other MNP modems at 2400 bps with error correction/
    compression

------------------------------------------------------------------------
Manufacturer           Toll Free       Charge Call     Support BBS 
============          ==============  ==============  ==============
Anchor                (800) 541-2318
Anderson Jacobson     (800) 438-8520  (408) 435-8520
Cardinal                              (717) 293-3000
Codex                                 (508) 261-4000 
Compucom              (800) 228-6648  (408) 732-4500  (408) 738-4990
Computer Peripherals  (800) 854-7600  (805) 499-5751  (805) 499-9646 
Digicom               (800) 574-2730  
E-Tech                                (408) 982-0270
Farallon                              (415) 596-9100
Fastcomm              (800) 521-2496  (703) 620 3900
General Datacom       (203) 574-1118
Hayes                 (800) 241-9625  (404) 441-1617  (800) 874-2937
Intel                 (800) 538-3373                  (503) 645-6275
Magic Modems          (800) 622-3475
Mastercom                             (213) 834-6666
Microcomm             (800) 822-8224  (617) 551-1000
Multi-Tech            (800) 328-9717
NEC                   (800) 222-4632  (408) 433-1250
Practical Peripherals (800) 442-4774  (818) 706-0333
Promethues            (800) 477-3473  (503) 624-0571
Radcal Vadic          (800) 482-3427  (408) 432-8008
Radcal Milgo          (800) 327-7909  (305) 846-1601
Shiva                 (800) 458-3550  (617) 864-8500
Telebit               (800) 835-3248  (408) 734-4333
Telenetics            (800) 822-4267  (714) 779-2766
USD                   (800) 631-4869  (205) 430-8000
USRobotics            (800) DIAL-USR  (708) 982-5001  (708) 982-5092

        
-----------------------------------------------------------------------

                          Price Comparisons
                          =================


Many Modem Manufactures offer BBS Sysop special prices directly, at
50% off retail price.  Then the Sysop must agree to use the Modem on 
the BBS for some set amount of time, and include a banner in the
logon screen mentioning the presence of the modem.

-----------------------------------------------------------------
Generic Brands         Retail          Sysop   

V.32 Only    EXT       $650-$1,000    ???? 
V.32/V.42    EXT       $700-$1,000    ????
V.32/V.42bis EXT       $700-$1,200    $339+

Software Included: Varies (most externals come without software)
Warranty: Varies 1-5 years
-----------------------------------------------------------------
Cardinal


V.32/V.42bis MNP 5 EXT       $350-$400    $300+

9600, 4800, 2400, 1200, 300, 1200/75 Baud Rates

V.32, V.22bis, V.22, V.21, Bell 103 & 212A Standards

AT Command set with Extensions, NVRAM, Auto Speed Conversion/Adaptive 
circuitry.

Software Included: None
Warranty: 1 year
-----------------------------------------------------------------
Hayes                    Retail      Sysop

Ultra V.32/V.42          $1,199      $599
V-Series V.42 (not V.32)   $999      $499
V-Series 9600              $799      $399

Software Included: None
Warranty: 2 years
-----------------------------------------------------------------
COMPUcom                 Retail      Sysop 

Speedmodem Champ (INT)    $169        N/A
Speedmodem Combo (INT)    $279        $169

The Combo includes BitFax and Voice-Mail software
Warranty: 5 years
-----------------------------------------------------------------
Intel                    Retail      Sysop

9600EX                     $799      $399

Software included: None
Warranty: 5 years
-----------------------------------------------------------------
Practical Peripherals    Retail      Sysop

V.32/V.42  EXT             $699      $339
V.32/V.42  INT              N/A      N/A

Software Included: None
Warranty: 5 Years

Note: Originally these modems had several incompatibilities with other
V.32 modems such as USR. I'm told that P.P. has now fixed the bugs, and
is now shipping a reliable product.
------------------------------------------------------------------
Telebit                   Retail       Sysop

T1000                      ???        ???
T1500 V.32                 ???        ???
TrailBlazer INT            ???        ???
Trailblazer EXT            ???        ???
T2500 V.32/V.42            ???        ???

(anyone have info on these?)
Warranty: 5 years
------------------------------------------------------------------
USRobotics                Retail       SysOp

Courier Dual Standard E   $1,595       $699 
Courier Dual Standard I   $1,395       $649 
Courier V.32/V.42 EXT     $1,099       $599   
Courier V.32/V.42 INT       $949       $577   
Courier HST 14.4  EXT       $995       $449
Courier HST 14.4  INT       $895       $405
DS Upgrade Kit for HST EXT  $599       $300
DS Upgrade Kit for HST INT  $499       $250
                                           
Software included: None
Warranty: 2 Years (extended warranties available for $25 per year)
------------------------------------------------------------------
Document updates:

Date       Release    Comments
----       -------    --------
10/30/90   1.0        Initial Release. Should have run a spell checker!
11/08/90   1.1        Spelling fixes, V.32bis update, Speedmodem update 
01/10/91   1.2        USR V.32bis Update, other minor corrections
01/15/91   1.3        USR V.32bis corrections, Speedmodem update, more spelling
                      fixes. Thanks to Remco Treffcorn
02/13/91   1.4        Minor corrections, thanks to Bill Garfield

** End-of-file **

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