Newsgroups: comp.sys.atari.st
Path: utzoo!lsuc!jimomura
From: jimomura@lsuc.on.ca (Jim Omura)
Subject: Re: RFI, the FCC, and STs (was re: Talking about other computers here)
Message-ID: <1990Dec7.115131.26377@lsuc.on.ca>
Organization: Consultant, Toronto
References: <1990Dec02.215601.7327@ecst.csuchico.edu> <1990Dec3.153120.27313@cunixf.cc.columbia.edu> <1990Dec3.173941.29280@cs.ucla.edu> <1990Dec3.195756.27537@cunixf.cc.columbia.edu> <479@aupair.cs.athabascau.ca>
Date: Fri, 7 Dec 90 11:51:31 GMT

In article <479@aupair.cs.athabascau.ca> rwa@cs.athabascau.ca (Ross Alexander) writes:
>cmm1@cunixa.cc.columbia.edu (Christopher M Mauritz) writes:
>>just pointing out that Atari has pulled the FCC-is-holding-us-up stunt
>>so many times in the past that maybe (just maybe) the fault lies at
>>Atari.  How many times can you tell your teacher that your dog ate your

...

> ... It took
>fairly heroic measures to get the intereference down to the point
>where I could recieve anything from other stations; lots of bypassing,
>coax cables, chokes, shielding, and physical separation were needed.
>Having done all that it works fine (good serial I/O, lotsa horsepower
>:-).
>
> ... and why are their machines
>so noisy?  Corner-shaving and cost cutting have limits, y'know.
>

     Well, yeah.  You guys have pretty much state the reality.
Atari has been aiming at cheap computing and that's your answer.

They leave the stuff as marginal as they can get away with
for RFI because anything you do about RFI costs money.
But taking it from the top, the problem starts with IO interfacing.
You can build a dirt cheap computer with no IO.  A grounded cage
does it.  But as soon as you start adding IO ports you've got
troubles.  The Atari ST is rich with IO ports, and not all
of the best possible quality.  You've got the 2 MIDI ports (the
basic spec of which looks noisy I might add -- not Atari's fault),
an RS-232C, semi-SCSI, Centronics, 2 joystick and cartridge port.
Take that "Centronics" port.  The original Centronics used every
other wire as a balance which could have helped cancelled "some"
RFI (doesn't help that much anyway really).  But the Atari doesn't
do anything with them.  Actually, I'd be happier them connected
for data reception like the Amiga.  But the only way to silence
that one is a *very* expensive fully shielded cable.  The cartridge
port should be given a bolt on metal "protector" when its not
in use.  If it was a Japanese company, maybe a hinged door would
have been included.  Also, I'm not sure what the keyboard looks
like if you take that apart.  I have a feeling you'll find it
an excellent source of interesting radio signals. :-)

      In passing, the most impressive *looking* computer I've seen
RFI-wise was the TI-99/4a.  I took this apart and it looked just
beautiful!  All this nifty shielding all over the place. . . .
It looked almost Mil Spec.  I have no real idea about how effective
the shielding was, but it certainly looked nice.  Another matter
about the basic PC boxes is that nobody has to research them
anymore.  A lot is known about them.  You just have to look at
a "good" example and copy it.  Be that as it may, a lot of IBM
related stuff has failed FCC over the years.  Not surprisingly,
from what I gather, a lot of it was IO stuff.
-- 
Jim Omura, 2A King George's Drive, Toronto, (416) 652-3880
lsuc!jimomura
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