Getty for ISC/Telebit T-2500 w/autobaud via the CONNECT msg?

[Bill Mayhew]

A rather inexpensive, if not the least expensive, v.32 modem of
credible qualtiy is made by GVC.  I purchased mine in single
quanity for $405.  Price for ten or more is $395.  GVC is based on
the ubiquitous Rockwell v.32 chipset engine and includes MNP level
and v.42 / v.42bis lap-m error correction and compression provided
by a Z-80 running Softart's MNP/v.42 firmware.  The command
processor is an 8031 with 32K of its own firmware.  The maximum
interface speed is 38400, so you can get full benefit of v.42bis on
a clean link.  The manual is relatively well written, but the v.42
commands are covered in a supplement that could be misplaced.
Fortunately, AT&H is an on-line manual that lists all of the many
commands.  There is EEPROM (not battery backed CMOS!) that can
store two configurations; the contents may be viewed with AT&V.

GVC was rated #2 in the PC Week v.32 modem poll just behind
Digicomm.  I don't currently have a line impairment test set, but
subjectively GVC performs on par with Digicomm and Hayes for noise
rejection and sensitivity.  I have a trunk circuit that I can dial
up that has a sync slip problem that renders non MNP 1200 baud and
2400 modems unusable.  I was able to hold a connection between the
GVC and Digicomm on that line at 9600 with the test light on the
GVC blinking regularly (confirming the sync slip) showing the error
correction.  Thoughput was better than 800 char / sec.

I work in a computer support center and have a chance to tear apart
the GVC modem and scrutiize it.  It is very well made from decent
materials.  I do not recommend the internal GVC 9600 (for IBM ISA
bus) for Unix users becuase the UART is only an 80C450.  This means
that you can't take advantage of interrupt overhead reduction by
employing the fas 2.08 driver and Nat. Semi. 16550 Uart chip.  The
80C450 on the GVC internal modem is a surface mount 40 pin chip
which makes its replacement with 16550 rather impractical.

To stay non-commercial, anybody that wants to know the vendor
should contact me via email.  I have no connection with GVC other
than as a user (who is now $405 less rich than before!)

PS: speaking of Digicomm, they now have a new firmware release that
supports v.42 lap-m, but not v.42bis.  The upgrade is free from
Digicomm technical support (ask for Dave).

Bill

-- 
Bill Mayhew      NEOUCOM Computer Services Department
Rootstown, OH  44272-9995  USA    phone: 216-325-2511
wtm at uhura.neoucom.edu   ....!uunet!aablue!neoucom!wtm
via internet: (140.220.001.001)