1) The old USR HST had a top transmission speed of 9600 bps.  This is before
taking into account any kind of MNP compression or whatever. Typical throughputs
with the old HST ranged from 1150 cps on an compressed file with the modem-
compression-disabled to 1900 cps on a text file with modem-compression-enabled.
 
2) The new USR HST is able to transmit data at 14400 bps (again, this is before
taking into account MNP compression, etc).  Typical thoughputs with the new HST
will range from about 1500-1600 cps on a compressed file with modem-compression-
disabled to about 2300-2400 cps on a text file with modem-compression-enabled --
this is assuming that you'ved opened your comm port at 38400 bps.
 
3) The Hayes v.42 modems are similar to the old USR HST described in #1 above.
However, you cannot "enable or disable" compression using the Hayes modems.  For
that reason you'll see throughputs as high as 1900 cps on text files but only
about 960 cps on compressed files.  The Hayes V-Series modems will ONLY
communicate at 9600 bps when connected to another V-Series modem.
 
4) Hayes v.42 modems can talk to any other MNP modem at 2400 bps (again before
MNP compression).  The v.42 implements MNP levels 1 thru 4 which excludes MNP
compression .. however, it still implements the ability to strip start and stop
bits so you'll still see throughputs of about 280 cps on a 2400 bps line.
 
5) The USR v.32 modem as well as the MultiTech v.32 modem run at 9600 bps and
will give you similar throughputs to those described in #1 above (i.e.  v.32
will give you slower transmission speeds than will the new HST's running at
14400).  The advantages of the "v.32 mode" are, however, that it provides you
with better "interactive response times" (i.e.  when typing) and it also will
talk to OTHER MODEMS that have implemented v.32.  By "other" I mean you should
be able to connect USR v.32's to MultiTech v.32's to any other v.32's.  The v.32
standard appears to be one that remain for some time to come ..  so purchasing
a v.32 modem may be a better investment if you are concerned about future com-
patibility.  However, v.32 still costs more than the older proprietary stds.
 
6) The USR Dual Standard is both a v.32 and an HST modem.  When it is in the
"HST mode" everything I said in number 2 above is true.  When it is in "v.32
mode" then everything I said in number 5 is true.  In other words in v.32 modem
you will not get the full speed advantage of your modem for file transfers. One
BIG advantage to the Dual Standard is that it is compatible not only with the
v.32 (future standard) but with all of the existing HST modems as well.  This
may or may not be a concern for you depending on who you connect to frequently.
 
7) Hayes is working on a v.32 modem that is similar to the v.32 description
given in number 5 above.  I cannot comment further on this modem due to lack of
details that have been given to me.  At this point in time it is unclear to me
whether Hayes' v.32 modem will include v.42 or MNP.  If it is v.42 then you will
be able to talk to it with a Dual Standard or a MultiTech v.32 but you will not
get the benefits of MNP's compression.  Perhaps in the future you will see
v.42's compression supported on those "other" modems instead.
 
Addendum - what is v.32?  What's the difference between it and v.42?
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The v.32 standard is a "modulation" standard.  I like to compare it to
the AM and FM standards used in radio broadcasting.  Not only are they
at different frequencies but they use different modulation techniques.
There are different modulation standards for 300, 1200 and 2400 baud.
The v.32 standard is a full duplex (data going both ways simultaneously
at the rated speed) standard for 4800 and 9600 bps connections.
 
The v.42 standard is an error correction standard.  It is a method by
which data is packetized and sent between modems to ensure that the data
that arrives at the receiving end is the same as what was transmitted.
It also includes the ability to compress data on the fly to enable
higher throughput without requiring a different modem modulation scheme.
 
MNP is another error correction standard.  In fact, the v.42 standard
includes MNP as an "alternate" method in case a modem is not v.42
compliant .. in other words as mentioned above v.42 modems can connect
with MNP modems and achieve a "reliable" connection.
 
As you can see, v.42 and v.32 are standards for two completely different
areas of communication.  In fact, you'll most likely discover that every
v.32 modem you find has v.42 or MNP in it.