Date   : Thu, 08 Dec 1983 18:21:06 PST
From   : Phil Lapsley <jlapsley%D.CC@berkeley>
Subject: U.S. Robotics S-100 1200 baud modem: a note

    I recently sent a request to Info-CPM about the U.S. Robotics
S-100 autodial modem, which is being advertised just about
everywhere for very low (< $400) prices.  I got a number of
responses, and was also sent a collection of reviews of various
cheap 1200 baud modems.

    Anyway, I just thought I'd add my reactions to the USR 1200
baud S-100 modem to the dung heap...

    First, *FLAME ON!* -- they didn't include schematics with the
creature.  To me, this is inexcusable.  When I get an S-100
board, I like to know what's in it, and I like to have a
schematic around to modify it if it comes down to that.  I have
sent them a letter about this, and we shall see whether it's
simply an oversight or if it's against their policy to include
schematics, or what.

    Second, the thing powers up in auto-answer mode.  While I'm
sure a lot of people like this, I don't.  I'd rather not have the
modem answer until I tell it to.  The manual suggests that I
could put something in my BIOS to disable this feature.  Well, I
could do that, sure.  But I'd rather have an on-board switch
which would enable/disable auto-answer upon reset or power up. 
As it is now, whenever I have my computer on and somebody calls,
I have to tell them to either hang up (and I'll call back) or
ride out the 17 odd seconds while the machine waits for a
response.

    Third, the manual reminds me a lot of the things I got with
our old IMSAI.  They are poorly written, poorly organized, and
seem to be photocopies, stapled together at one corner.  Still,
it does contain the information -- it's just a matter of finding
it.

    Fourth, the on-board "speaker" (it looks like more of a
buzzer) produces some rather raspy noises which are alleged to be
the sounds of the call in progress.  Well, maybe, but I'd rather
listen through a small 8 ohm speaker, which I intend to hook up
later this evening.

    Finally, when the board powers up, it is in the "off-hook"
state.  That is, it has the phone line off hook.  This means, of
course, that until you tell it to "drop" the line, your line is
busy and cannot be used even for outgoing calls, as the modem
puts a rather annoying hiss on the line.  The manual was good
enough to suggest a fix for this -- it mentions a diode which can
be cut out.  I have done this, and it now behaves a bit better. 
It [the manual] also points out that this could be fixed by
adding something to one's BIOS.

    Now comes the surprising part: It's really a pretty good
product.  My flaming above is really about some pretty trivial
matters.  I have the feeling that U.S.R. will come across with a
schematic for the beast, and then I can sit down and do some
modifications.

    So, the end result is something like this:  If you don't mind
the aforementioned things, and/or if you are looking for an
inexpensive S-100 1200 baud modem, the U.S.R. S-100 might be
worth looking into.

                                       Phil

                             (jlapsley%D.CC@Berkeley)