HDTenEightyP/NetNews huggingface dataset:
From: medin@catbyte.b30.ingr.com (Dave Medin)
Subject: Re: Dolby B/C? (A??)
Reply-To: medin@catbyte.b30.ingr.com
Organization: Intergraph Corporation, Huntsville AL
Date: Wed, 29 Jul 1992 19:49:39 GMT

In article <1992Jul28.113002.607@cmkrnl.com>, jeh@cmkrnl.com writes:

|> Full-bandwidth companders are fairly old hat.  What Dolby A nr did that was new
|> was to derive four different control signals from four different audio bands,
|> and use them to control companders which operate only in those respective
|> bands.  The result was a marked reduction in "pumping" and "breathing" and
|> "noise tails" which were associated with simple full-bandwidth companders. 
|> 
|> dbx, incidentally, is a sort of a cross-breed.  Its compander operates on the
|> entire audio band, but its control signal is derived not from a full-bandwidth
|> "level" but from a proprietary filter network that samples just a few key
|> frequencies.  

Close. dbx has simultaneous wideband AND multiband companding. The bands and
the companding algorithm depend on the dbx type (I, II, or III, while
MTS TV uses a combination of the above along with fixed EQ). The published
algorithms exist in dbx's patent filings.

-- 
 --------------------------------------------------------------------
       Dave Medin			Phone:	(205) 730-3169 (w)
    Intergraph Corp.				(205) 837-1174 (h)
       M/S GD3004
  Huntsville, AL 35894 		Internet: medin@catbyte.b30.ingr.com
				UUCP:  ...uunet!ingr!b30!catbyte!medin

   ******* Everywhere You Look (at least around my office) *******

 * The opinions expressed here are mine (or those of my machine)
From: jeff@hpuplca.nsr.hp.com (     Jeff Gruszynski)
Newsgroups: sci.electronics
Subject: Re: Airport X-Rays
Date: 29 Jul 92 01:07:46 GMT
Organization: Hewlett-Packard Neely Golden Gate Area (Northern Calif.)

> In sci.electronics, polish@cs.columbia.edu (Nathaniel Polish) writes:
> 
>   I think we should clarify the model for how an airport x-ray damages
>   a magnetic medium.  Certainly large fields will degauss a floppy but this
>   is unlikely except as noted from the motors.  The real problem with x-rays
>   is that they are high-energy radiation.  They can cause small ionizations
>   on the surface of the disk.  If the ionizations are small relative to the 
>   size of the magnetic domains, then there is no visable problem.  As the 
>   media get denser, the domains get smaller and the problems appear.  However,
>   modern airport x-ray equipment is very sensative and they use very weak 
>   sources -- mostly to protect the workers.

You'd probably need mega or giga Rad X-ray levels before you'd affect the
magnetic media.  In a previous life I worked with radiation testing hardened
memories including both semiconductor and magnetic types.  In the latter
the magnetic memory cells were never the issue, but rather getting the
semiconductor support circuitry to keep up with what the magnetics could
take.  The cell sizes of these magnetic memories (bubble and
magnetoresistive) were smaller than the domain size of most floppies.

Probably a bigger threat to floppies, tapes, etc. would be the HV
supplies and fields generated by the E-beam in the X-Ray tube, **if even
this**.

Jeff
From: berger@atropa (Mike Berger)
Newsgroups: sci.electronics
Subject: Re: PC masks from a laser printer??
Date: 27 Jul 92 19:31:38 GMT
Organization: University of Illinois at Urbana

MATGBB@LURE.LATROBE.EDU.AU (BYRNES,Graham) writes:
>Up until now I have made my PCB's using donut and tape transfers on
>overhead proj film, exposing Electrolube +ve resist on the copper.
>However, as I have now entered the compuer age and bought a cheapy
>PCB CAD program, I need to produce masks from a laser printer.
>I tried the obvious (direct print on transparency), but the result
>was sufficiently porous that the copper looked like a 1/2 tone printers plate
>after etching. What should I do? I'm going to try inking over the printed
>bits on the mask, but that doesn't leave me a long way in front of the 
>stick on donut method.
*----
Assuming your laser printer prints EXACTLY the right size (most of the
ones I've worked with have some variation.  Are they precise enough for
a couple foils between 1/10" spaced leads?), you could have a
photopositive (or negative) transparency made.  Ask for high
contrast, and it should be sufficiently opaque.
--
	Mike Berger
	Department of Statistics, University of Illinois
	AT&TNET     217-244-6067
	Internet    berger@atropa.stat.uiuc.edu
From: adams@chuck.dallas.sgi.com (Chuck Adams)
Newsgroups: sci.electronics
Subject: Chebyshev Low-Pass Filters
Date: 28 Jul 92 21:08:31 GMT
Organization: Silicon Graphics, Inc.

All you PSPICE users out there.  i want to know what you get for
VDB(3) for the following Chebyshev 5-Element Low-Pass Filter at
7.0, 8.0, 10.0, 14.0, and 21.0 MHz.  Any help greatly appreciated
as i am checking Spice 2g.6 output.  i don't need all the points
unless you email me the output, which is too much trouble on your
part.


AC ANALYSIS OF CHEBYSHEV FILTER
*
VIN  1 0 AC 1
C1   1 0 470PF
R0   1 0 50
L1   1 2 1.45UH
C2   2 0 820PF
L2   2 3 1.45UH
C3   3 0 470PF
R1   3 0 50
.PRINT AC VDB(3)
.AC LIN 71 7MEG 21MEG
.END

here are the values i get.

7.0  1.567e-01
8.0 -3.460e+00
10. -1.565e+01
14. -3.088e+01
21. -4.663e+01

that is, if i can still type as good as i could when i won the UIL
class b typing contest in 195x where x is for me to know.  88 wpm/5 min
no erros on a manual typewriter.  no big deal as IBM ruined my speed
with an 029 keypunch.  :-)

many thanks to all in advance,



-- 

   Chuck Adams, Southern Education Center
   Silicon Graphics, Inc.
   15280 Addison Road, Suite 100
   Dallas, TX  75248

   (214) 788-0957 (fax)
   (214) 788-4122 (voice)
   
   K5FO @ 65wpm cw ---  adams@sgi.com

--------------------------------------------------
Heisenberg may have been here.  *
Newsgroups: sci.electronics
Subject: Magnetic Tape Developer
From: butler@vax.sonoma.edu
Date: 29 Jul 92 14:28:50 -0800
Organization: Sonoma State University

We used to use a magnetic tape developer called Kyread.  Does anyone know
where I can get more or what kind of chemical(s) it is?  I'm hoping it's
a common item that I can get from our chemistry department because I'll
have difficulty buying some when the State of California has no money or 
budget.     

Thanks,

Bob Butler (butler@vax.sonoma.edu)
Sonoma State University, Computer Shop
Newsgroups: sci.electronics
From: kpopple@imp.sim.es.com (Ken Poppleton)
Subject: Re: Are there any large PALs/GALs?
Reply-To: kpopple@imp.sim.es.com (Ken Poppleton)
Organization: Evans & Sutherland Computer Corp., Salt Lake City, UT
Date: Thu, 23 Jul 1992 19:20:51 GMT

Take a look at the AMD MACH parts.  The smallest is a bit larger than
2 22v10's and costs $15 a few bucks more than the 2 parts it replaces.  It also 
has  burried registers.  And the AMD PALASM program for doing the login equations 
runs about $125.

-----------------------------------------------------------------------
Ken Poppleton 
kpopple@imp.sim.es.com
-----------------------------------------------------------------------
Newsgroups: sci.electronics
From: rvk@blink.att.com (Bob Kline)
Subject: blue laser
Organization: AT&T
Distribution: usa
Date: Tue, 28 Jul 1992 16:16:35 GMT
Summary: blue laser exists, operates at -300 F
Keywords: blue laser


	Sony announced a blue laser device, with a wavelength of about
	440 nm.  this might enable a three-fold increase in storage 
	density.

	what some sources (e.g., The NY Times ) failed to mention is that
	the devices work at something like -300 F.  it's possible that the
	devices can be made to work at "room" temperature, but don't hold
	your breath.  seen any room temperature superconductors lately?

	-r. kline
	rvk@blink.att.com

Newsgroups: sci.electronics
From: cab@col.hp.com (Chris Best)
Subject: Re: Radar Detectors, and Radar Detector Detectors
Date: Fri, 24 Jul 1992 15:12:34 GMT
Organization: your service

> I'm sure it is....maybe we'll soon have combination radar detectors and
> radar detector detector detectors.  The cops will, of course, be 
> equipped with radar, radar detector detectors, and radar detector detector
> detector detectors.

----------

...and Cincinnati Microwave will be raking it in from both sides.
From: wilker@hopf.math.purdue.edu (Clarence Wilkerson)
Newsgroups: sci.electronics
Subject: Re: TOUCHtone "emulator"
Keywords: touchtone
Date: 28 Jul 92 22:48:49 GMT

Why not buy a cheap touchtone phone?
-- 
Clarence Wilkerson      \ Bitnet:       wilker%math.purdue.edu@purccvm
Prof. of Math. (topology)\ Internet:    wilker@math.purdue.edu
Dept. of Mathematics      \ messages:   (317) 494-1903, FAX 494-0548
Purdue University,         \ office:    (317) 494-1955 (voice/modem)
W. Lafayette, Indiana 47907 \ 
Newsgroups: sci.electronics
From: tchannon@black.demon.co.uk (Tim Channon)
Subject: Dallas Semiconductor Clock Chip 
Distribution: world
Organization: null
Date: Fri, 24 Jul 1992 20:33:25 +0000

> I am presently working on a project which uses a 6811 and
> a clock chip as part of a timer which will be deployed 
> in the ocean for up to a year at a time. The timer controls
> and instrument which takes water samples for climate
> change research...
> 
A good chip for many application is the ICM7170 (or similar number from other 
source(s)).

This is a nice chip to use. Unusually (for clock chips) it is fast enough  to 
hang  directly  on  the bus (300ns), has the alarm you want during powerdown, 
time from 1/100s to years inc. leap years, has a latch instruction  for  easy 
reading,  on  board  power switchover. It is intended for single lithium cell 
backup and screened parts to 2ua on 32k xtal are available.

I've used  it  for  critical  applications  without  problems  in  commercial 
systems.   Critical  means  one  failure  costs  as much as I'm paid in three 
months. I hate leap years, and will not be available starting 1999!

  TC. 
    E-mail: tchannon@black.demon.co.uk or tchannon@cix.compulink.co.uk
                                
Xref: sparky sci.electronics:13473 rec.audio:10947 alt.folklore.computers:11290
From: bbehlen@soda.berkeley.edu (Vitamin B (Brian Behlendorf))
Newsgroups: sci.electronics,rec.audio,alt.folklore.computers
Subject: Re: Two-sided CD's *DO* exist! (was Re: Life after CDs)
Date: 28 Jul 1992 16:40:08 GMT
Organization: U.C. Berkeley, CS Undergraduate Association
NNTP-Posting-Host: soda.berkeley.edu

	A few years ago I saw a Jimi Hendrix bootleg CD that was double-sided;
no printing on either surface, and it held 130 minutes of music.  Supposedly
it worked in 90% of CD players.... 

	Brian

Xref: sparky sci.electronics:13480 rec.audio:10949 alt.folklore.computers:11296
From: isbell@ai.mit.edu (Charles L Isbell)
Newsgroups: sci.electronics,rec.audio,alt.folklore.computers
Subject: Re: Two-sided CD's *DO* exist! (was Re: Life after CDs)
Date: 28 Jul 92 16:25:04 GMT
Article-I.D.: pop-tart.ISBELL.92Jul28122504
	<aldavi01.712267502@starbase.spd.louisville.edu>
Followup-To: sci.electronics
Organization: MIT Artificial Intelligence Laboratory
In-reply-to: aldavi01@draconis.spd.louisville.edu's message of 27 Jul 92 20:05:02 GMT

aldavi01@draconis.spd.louisville.edu (Arlie Davis) writes:
|One of Monty Python's albums (Matching Tie and Handkerchief, I think it
|is called) has *three* sides.  One side is normal, and one side has two
|grooves.  Depending on where you start the needle, you get one of the
|two tracks.

De La Soul did that for one of their twelve inch singles (Me Myself
and I) from _3 Feet High And Rising_.  Ahhh, the wonders of
technology.
--
Peace.
"Well, I would -- if they realized that we -- again if -- if we led them
 back to that stalemate only because our retaliatory power, our seconds,
 or strike at them after our first strike, would be so destructive they
 they couldn't afford it, that would hold them off."
                -- President Ronald Reagan, on the MX missile
                                   -\--/-
    Don't just adopt opinions     |  \/  |       Some of you are homeboys
          develop them.           |  /\  | but only I am The Homeboy From hell
                                   -/--\-
Newsgroups: sci.electronics,rec.audio,alt.folklore.computers
From: lasner@watsun.cc.columbia.edu (Charles Lasner)
Subject: Re: Life after CDs
Reply-To: lasner@watsun.cc.columbia.edu (Charles Lasner)
Organization: Columbia University
Date: Thu, 23 Jul 1992 22:19:24 GMT

In article <14mdkjINNb4m@grapevine.EBay.Sun.COM> smckinty@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC) writes:
>In article <1992Jul23.041115.20377@bilver.uucp>, bill@bilver.uucp (Bill Vermillion) writes:
>
>	> 
>	> They [Sony] couldn't break themselves of thinking 12" - ala LP's or
>	> LDs.  I took Philips to come up with an under 5" disk.  And
>	> then Sony and Philips got together and standardized on the
>	> current 12cm disk that sped'ed out at 74 minutes.
>	> 
>	> 
>There is a story (probably apocryphal, anyone know?) that the 74 minutes
>time was chosen because it was just long enough to hold the Sony MD's wife's favourite piece of classical music...
>

The part I heard was that this requirement wasn't going to work at the
designated sample rate of 48 KHz, so they cut it back to 44.1 to squeeze it
in.

cjl

Newsgroups: sci.electronics
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: unknown chip in snes controller. please help.
Date: Tue, 21 Jul 1992 20:54:54 GMT
Organization: U of Toronto Zoology

In article <14d33tINNpkh@stanley.cis.Brown.EDU> ST403383@brownvm.brown.edu (Thai Pham) writes:
>Manufacturer's logo:
>
>              \ \
>            /  \ \      doesn't look like Motorola, Matsushita?

Looks like Microchip Technology's logo.  However, the numbers don't seem
to match up with anything in their databook.  They do sell the PIC series
of microcontrollers; perhaps your chip is a custom version of one of them.
(The standard PICs don't come in 20-pin packages.)
-- 
There is nothing wrong with making      | Henry Spencer @ U of Toronto Zoology
mistakes, but... make *new* ones. -D.Sim|  henry@zoo.toronto.edu  utzoo!henry
From: adw@cci632.cci.com (Allen Williams (co-op))
Newsgroups: sci.electronics
Subject: Green Layer on Circuit Boards?
Date: 21 Jul 92 13:46:01 GMT
Organization: Computer Consoles Incorporated


 I have made some circuit boards using the method posted in this fine
newsgroup a few months ago. This method uses the photoresist coating,
developer, etchant, and tinner. I am glad to say that my boards have
taken a giant leap in quality, up from the old days of drawing circuits
with a etch resist pen and having problems with soldering in components
because the board was so oxidized a week later. I wish I could remember
who it was that posted it (I don't have the document handy) but the
appropriate parties probably know who they are.

 However, one step that I think would be a good addition is the green
layer of plastic insulation that commercial circuit boards have. I've looked
in the Mouser and Digi-Key catalogs, and can't find anything that looks like
the type of insulation that would go on top of the traces.

 Is it possible to add this layer of green insulation on do-it-yourself
boards? Or do you have to cut all these holes for the pads before applying
it, making it uneconomical to use unless you make ten thousand copies using
a cutter press? Or is it applied by using big and expensive machinery? 

 Although it's not absolutely necessary to have insulated traces, I feel 
that it would be better in the long run to reduce the chances of short
circuits as boards tend to accumulate dust and crud during long term use.
                      

 Any advice, pointers, and help is deeply appreciated.

                                                        Derrick
From: kolstad@cae.wisc.edu (Joel Kolstad)
Newsgroups: sci.electronics
Subject: Re: 7 seg. Hex display driver IC?
Date: 26 Jul 92 02:48:59 GMT
Distribution: na
Organization: U of Wisconsin-Madison College of Engineering

In article <55066@mentor.cc.purdue.edu> falatic@mentor.cc.purdue.edu (MacGyver) writes:
>
>	Hi! I am looking for a chip to convert BCD (actually, straight 4 bit 
>binary) to drive a 7 segment LED display, and to display 10d to 15d in
>Hexadecimal (A-F). I need something LIKE a 7447 driver, but that one does not 
>treat 10d-15d the way I need. Anyone who can help, please reply thru E-Mail
>if possible, or post here.

Use a 32 by 8 EPROM -- a 74S288.  The cost is <$2.  For 32 locations you
can program this by hand, using only DIP switches, LEDs (for verifying
stuff) and wires.  By a few more parts that you need, because you'll want
to use one to experiment with.  I've done this myself, and it works well.
I kept a few small circuit boards around that do this function, and this
function only -- they're sometimes useful for debugging microprocessors.
Also, you can do something creative with the $10-$1f.  In a box I built for
IBM, it spells out my name up there.

PALs would be fine too, but you really need a programmer then.  There ARE
some chips that already do this all by themselves, but they're a little hard
to find and not much cheaper.

						---Joel Kolstad
Newsgroups: sci.electronics
From: wtm@uhura.neoucom.edu (Bill Mayhew)
Subject: Re: Letters to the Editor:  Blazing Ta
Organization: Northeastern Ohio Universities College of Medicine
Date: Tue, 28 Jul 1992 14:55:38 GMT

I don't know if the ignition circuit I looked at is exemplary of
all such systems, but the coil is charged through a ballast
resistor.  I presume the ballast resistor is used to avoid frying
the points in the distributor.  When the points open, the collapsing
field dumps though a capacitor, again I presume to avoid burning up
the points.  A prudent engineer, I would suspect, would take
advantage of resonance in chosing the coil and capacitor so as to
maximize the output voltage.

The use of ballast resistor also permits the current in the coil to
be large enough to provide maximum flux density in the core.
During cranking there is a significant voltage drop; the starter
solenoid contactor may have a second contact to bypass the ballast
while starting to assure the coil gets sufficient current to
maintain usable spark.


-- 
Bill Mayhew      NEOUCOM Computer Services Department
Rootstown, OH  44272-9995  USA    phone: 216-325-2511
wtm@uhura.neoucom.edu   (140.220.1.1)
Xref: sparky sci.electronics:13224 comp.sys.ibm.pc.hardware:20196
From: hamish@werple.pub.uu.oz.au (Hamish Moffatt)
Newsgroups: sci.electronics,comp.sys.ibm.pc.hardware
Subject: Re: Airport X-Rays
Date: 23 Jul 92 11:50:38 GMT
Organization: Werple public-access Unix, Melbourne

smckinty@sunicnc.France.Sun.COM (Steve McKinty - Sun ICNC) writes:

>The X-rays themselves won't do any damage, unless you're carrying something
>like 1000ASA photographic film, but they use pretty hefty electromagnets
>to focus the beam, so I never trust floppies or tapes in them, just in case.

Someone once told me that floppy disks have huge ASA speeds - much bigger
than 1000ASA. No idea if this is true though.... (if true the X-rays could do
damage too..)


Hamish

-- 
Hamish Moffatt, hamish@cloud.pub.uu.oz.au -and- hamish@werple.pub.uu.oz.au.
Note new path to cloud: ...!eyrie.img.com.au!cloud      Thank you. :-)
From: shopper@.ucsd.edu (Steve Hopper)
Newsgroups: sci.electronics
Subject: TOP SECRET Consumertronics
Keywords: Radio Electronics
Date: 31 Jul 92 16:55:36 GMT
Organization: CSE Dept., U.C. San Diego
Originator: hopper@empyrean.ucsd.edu


There is an ad in this months Radio-Electronics (in the catalog
insert section) on page 60A28 which sells all kinds of amusing
information.  I'm specifically interested in the Radionics Manual.

Has anyone ordered anything from them before and is the info worth
the price they get for it?  I know some of this can be found on
various BBS, etc.

Steve
From: jeh@cmkrnl.com
Newsgroups: sci.electronics
Subject: Re: Life after CDs
Date: 30 Jul 92 00:55:12 GMT
Organization: Kernel Mode Consulting, San Diego, CA

In article <1992Jul27.212455.18334@ole.cdac.com>, ssave@ole.cdac.com 
(Shailendra Save) writes:
>    The dots are spaced out more as you go to the outer edge of the disc, since
> the radial speed increases as you go from inside to the outside. I wish they could
> decrease the speed of the disc as the laser pickup reaches the outside of the disc, 
> and store more stuff on it.  What do you think?

What you're asking for is how CDs work *now*.  That's why they're called 
'constant linear velocity' (CLV).  The rotational speed is reduced as the
pickup moves from inner to lower tracks.  Thus the dots-per-linear-inch is the
same on all tracks, inner and outer.  

	--- Jamie Hanrahan, Kernel Mode Consulting, San Diego CA
Internet:  jeh@cmkrnl.com, hanrahan@eisner.decus.org, or jeh@crash.cts.com
Uucp:  ...{crash,eisner,uunet}!cmkrnl!jeh
From: brianr@tekig1.PEN.TEK.COM (Brian E Rhodefer)
Newsgroups: sci.electronics
Subject: Re: 8051 help needed urgently!
Date: 30 Jul 92 22:12:47 GMT
Reply-To: brianr@tekig1.pen.tek.com
Followup-To: poster
Distribution: na
Organization: Tektronix, Inc., Beaverton,  OR.

In article <1992Jul30.165112.10990@ole.cdac.com> ssave@ole.cdac.com (Shailendra Save) writes:

   (describing his inaccurate mental model of an 8051 microcontroller)
>
>   When you clear a port pin, it is pulled to a tristate 1. It does not
>put a 0 onto the pin.  I would think you want to write a "0" onto the
>port to turn the led off.
>

Rubbish.  Clearing (i.e., using the CLR <bitnumber> instruction)
port pins of an 8051 family processor emphatically *does* set them
to 0;  to the best of their current-sinking ability, anyway.
Nothing tristate about it.

There are complications if the Port pin is one of the Port 0 or Port 2
pins that's implementing an external memory bus.  Any external memory
or code access will rewrite the Port 0 data output latch to all 1s,
and temporarily replace the state on Port 2 pins with the upper 8 bits
of external address (for code fetches, or data-pointer indirect reads only;
R0 or R1 indirection leave P2 alone).

Brian Rhodefer
Xref: sparky sci.electronics:13339 rec.audio:10846 alt.folklore.computers:11156
From: lasner@watsun.cc.columbia.edu (Charles Lasner)
Newsgroups: sci.electronics,rec.audio,alt.folklore.computers
Subject: Re: Life after CDs
Date: 26 Jul 92 15:53:37 GMT
Article-I.D.: news.1992Jul26.155337.14069
Reply-To: lasner@watsun.cc.columbia.edu (Charles Lasner)
Organization: Columbia University

In article <ERIC.92Jul23182226@napa.telebit.com> eric@telebit.com (Eric Smith) writes:
>>>On Thu, 23 Jul 1992 22:19:24 GMT, lasner@watsun.cc.columbia.edu (Charles Lasner) said:
>> The part I heard was that this requirement wasn't going to work at the
>> designated sample rate of 48 KHz, so they cut it back to 44.1 to squeeze it
>> in.
>
>I seriously doubt that, since PCM recording equipment already existed that
>used 44.056 KHz sampling, whereas I don't think anything in mass production
>used 48.0 KHz sampling at that time.
>
>Cheers,
>Eric


But PCM is a different technique; it might suggest to some marketroid a 
number to shoot for, but not much else.

48.0 is the standard pro sampling rate used before and since.  When Phillips
announced their format, soon thereafter I remember a Sony digital processor
vaporware announcement about dual rate capability, etc.

cjl
From: jsykes@dadd.ti.com (Jonathan Sykes)
Newsgroups: sci.electronics
Subject: Re: Green Layer on Circuit Boards?
Date: 22 Jul 92 18:38:26 GMT
Reply-To: jsykes@dadd.ti.com
Organization: Texas Instruments Inc

I could buy stuff in England that you just sprayed on the board immediatly
after tinning. You didn't need to mask out the solder pads - the film just
evaporated around the touch of a soldering iron. Maybe you can get it here
too - it was very easy to use.

---
           __o
           \<,
_________()/ ()_______________________________________________________________
Jon Sykes                                                   jsykes@dadd.ti.com
Design Automation Div.                                          (214) 997-2916
Texas Instruments Inc. Dallas, Tx.        
Newsgroups: sci.electronics,comp.sys.ibm.pc.hardware