Reports on Trailblazer modems (especially with 3B2 and IBM PCs)

[Bill Mayhew]

Arrrrrrrrrgh!  I think somebody ought to fire Marks and Stone (the
authors of the PC Mag article).  I don't know what sort ofline
impairment tests they did, but they must have been very severe to
make the Trailblazer have a poor showing.  I have done such things
as shout into the receiver or dial DTMF tones while my trailblazer
is doing a transfer and it never loses its connection.  If one
makes enough racket on the line, the Trailblazer will detect that
it has received several bad packets in a row, then stop and go
through the training sequence over again.

The trailblazer is the only modem is the only unit I know that has
special firmware supprot for xmodem, kermit and UUCP g protocol.
With the built in firware "spoofing" algorithms, I routinely get
data transfer rates on my home computer that are equal to the
transfer rates between our Vax and the computer in my office at
work that has  a dedicated line.  (Typically 880 char/sec when the
Vax is lightly loaded, talking on a 9600 bps port).

The trailblazer also provides sterling performance at 1200 and 2400
bps due to its internal adaptive line equalizer.  I can not get a
hayes smartmodem, for instance, to connect dialing from my home to
my office.  The Trailblazer has no problem.  (There is some sort of
sharp high frequency roll-off on the line that gives modems without
equalizers fits.)

The only thing bad I can say is that there appear to have been bugs
in the Telebit version 3.xx firmware that made MNP error correction
not work when other brand modems called into a Trailblazer.  This
seems to have been fixed in 4.xx firmware, as users routinely dial
in with MNP modems into my 3b1 at home.

I really wonder if the guys at PC Mag actually tested the
Trailblazer, of if they just read the glossy press release and
wrote something they thought would sound good.

If you want to sway your bosses to buy a Trailblazer, show them an
article in Unix World by John Blair -- I think it was in the
January '88 issue, but I am not positive.

About the only modem I know of that does as well at rejecting line
impairments at 1200 baud is the 1200 baud internal modem that IBM
sells for its PS/2 microchannel products.  (By the way, IBM's modem
is manufactured by Racal-Vadic, in case you were wondering.)

--Bill