HDTenEightyP/NetNews huggingface dataset:
From: firby@avarice.uchicago.edu (Jim Firby)
Subject: Looking for dual ported memory chip
Organization: University of Chicago Computing Organizations
Distribution: usa
Date: Fri, 21 Aug 1992 13:46:29 GMT

I'm looking for a good dual-ported memory to put between a
microcontroller and a VME bus.  A pointer to a manufacturer
is all I need.

Thanks.

Jim
(firby@cs.uchicago.edu)

Newsgroups: sci.electronics
From: af954@yfn.ysu.edu (Maoee Tsen)
Subject: A strange Mac 9" monitor display problem
Reply-To: af954@yfn.ysu.edu (Maoee Tsen)
Organization: St. Elizabeth Hospital, Youngstown, OH
Date: Thu, 13 Aug 1992 18:06:07 GMT

Good Day!  Netters,
 
I have one Mac 9" monitor display problem.  The display on the top
is distorted vertically, the bottom half of the menu is displayed
from the bottom of the menu bar to the top of the screen display
with black lines inserted between the horizontal lines; while the
top half of the menu bar is displayed from the top of screen display
to about one inch down from the top with black lines inserted.
The lower part of screen display is fine.  If I adjust the height of
screen display to about 3 inches, the display is fine.
 
When I adjust the screen height, the bottom edge of the screen respond
quickly, while the top screen edge expand or shrink gradually, take
several seconds to get to the right size of screen.
 
I also check the cut-off adjustment, the scan lines did not show evenly
from top to bottom of screen.  The scan lines density decrease gradually
from top to bottom of screen.  The scan lines did show up about 1/8"
outside the top of 'normal' screen display and within the bott
m edge
of screen display.
 
Does anyone know that's a problem of CRT, CRT circuit, the improper
signal frequencies or other problems?  Thanks in advance.
 
-Maoee
-- 
-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-==-
Maoee Tsen,   tsen@chemsun.chem.umn.edu   af954@yfn.ysu.edu
Dept. of Chemistry, Univ. of Minnesota, Minneapolis, MN 55455-0431
####
From: adrian@csqx.cs.rhbnc.ac.uk (A Johnstone)
Newsgroups: sci.electronics
Subject: Books on IBMPC hardware internals
Date: 19 Aug 92 09:35:23 GMT
Reply-To: adrian@csqx.cs.rhbnc.ac.uk (A Johnstone)
Organization: Dept of Comp Sci, Royal Holloway & Bedford New College Uni London


 
I'm trying to gather a comprehensive list of books and other material on the PC.
I DON'T mean those books that tell you what a hard disk is, and how to fit an
expansion card. I am interested in real circuit and timing information, and
system software books that cover the details of interrupt and DMA handling. It
seems to me that there are very few such texts around -- perhaps this is a 
reflection of our new software oriented hobbyist community, i.e. all the hardware
hackers have sold out ;-)

Anyway, I include below my existing small list, and I would be very glad to hear
about any others out there, as well as magazine articles and on-line network
documents.

 

"The IBM PC from the inside out" revised edition, Murray Sargent III and Richard
L. Shoemaker, Addison Wesley, 1986, ISBN 0-201-06918-0

Covers assembly language and has some (not much) hardware interfacing information.
Revised edition includes some info on AT, but, again, not much. 
Not a great book unless you are completely new to the game. Also typeset in 
horrible sans-serif daisywheel (remember them?) typeface.

"Handbook of software and hardware interfacing for IBM PCs" Jeffrey P. Royer,
Prentice Hall, 1987, ISBN 0-13-381849-7

Very useful coverage of BIOS, DOS file structures and quite advanced interfacing,
including DMA, wait state generation and interrupts. XT only  (sigh). 
Recommended but a bit out of date.

"Interfacing to the IBM personal Computer" second edition, Lewis C Eggebrecht,
Sams, 1990, ISBN 0-672-22722-3

The author was the original PC designer, and no he doesn't explain why PC
interrupt lines are active high... However this book has the virtue of being
up to date with good coverage of XT, AT and PS/2 MCA buses. Lots of useful
hardware info and examples, although he fights shy of giving program listings
which is a shame. Highly recommended.

IBM technical manual for the PC. Has all the schematics and a BIOS listing but
no advice as to design strategies. I believe there are equivalent volumes for
the XT and AT, but I don't have them.

 
                             Adrian
From: myers@hpfcso.FC.HP.COM (Bob Myers)
Date: Thu, 13 Aug 1992 20:16:08 GMT
Subject: Re: Building the Perfect Notebook
Organization: Hewlett-Packard, Fort Collins, CO, USA
Newsgroups: sci.electronics


Not again....not AGAIN!......NOT AGAIN!!!!!...(somebody, please restrain me!)


And now, the congregation will kindly repeat the Holy Mantra of Nicads along
with Brother Bob:

There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....
There's no such thing as nicad memory.....

.....and all together now, AHHHHHHHHHHH-MENNNNNNN!!!!!!!!!!!!


Bob Myers            | "One man's theology is another man's belly laugh." 
myers@fc.hp.com      |                     - Lazarus Long/Robert A. Heinlein
                     |                                
Newsgroups: sci.electronics
From: esrne@warwick.ac.uk (Mr P I Neaves)
Subject: 74ACTXXX logic
Organization: Computing Services, Warwick University, UK
Date: Thu, 20 Aug 1992 18:16:54 GMT

Has anybody out there had any experiance designing with
74ACTXXX logic ?

I have had SEVERE noise and switching problems with a
design employing 74ACTXXX and 74LSXXX devices.

Removal of the 74ACTXXX devices and replacement with 74LS
devices fixed the  problem.

All the "nice" things were done - lots of decoupling - four layer
board with groundplanes etc.

Thanks for help - replys to email at

esrne@clover.csv.warwick.ac.uk

Phil.
Newsgroups: sci.electronics
From: jep@miles.com (Joseph Perry)
Subject: Re: EIA-232 cable length restrictions
Followup-To: sci.electronics
Organization: Miles Inc., Diagnostics Division, Elkhart, IN
Date: Wed, 19 Aug 1992 16:42:50 GMT

In article <1992Aug18.071452.7706@aero.org> helfman@aero.org (Robert S. Helfman) writes:
>In article <1992Aug17.192021.4354@miles.com> jep@miles.com (Joseph Perry) writes:
>>I'm trying to determine the maximum cable length for EIA-232 connections.  
>>EIA-232 specifies that the effective shunt capacitance of the receiver 
>>side of the interchange circuit be no more that 2500 picofarads.
>>
>.....Stuff deleted......
>
>>Have I missed something in my measurements and analysis or is the EIA-232
>>standard overly conservative in limiting cable length?
>
>It is VERY conservative. We run terminals at 9.6k and printers at
>19.2 using twisted pair, unshielded, running in bundles with dozens of
>other similar circuits, all over the building. Runs of three hundred feet
>are typical. No hay problema (there's no problem).

I wasn't clear enough about what I really wanted to know.  I know that 
many EIA-232 drivers can drive more than the 2500 pF load as required by 
the standard and that a load capacitance of more than 2500 pF can be 
tolerated especially at baud rates below 20,000 bps.

My real concern is how to estimate the capacitance of a shielded cable as
seen by a driver.  The appendix in the EIA-232 and EIA-562 standards
describes Cm as the mutual capacitance between conductors and Cs as the
capacitance from a conductor to the cable shield.  Cm is often specified
for the cable.  Cs should also be specified, but if not, a good rule of 
thumb is Cs = 2 * Cm.

The way I read the appendix in the standards, the total cable capacitance, 
Ct, as seen by a driver in a shielded cable is:
  Ct = Cm + Cs 
     = Cm + 2 * Cm 
     = 3 * Cm

This makes sense to me only if the load was truly made of capacitors.  If 
you consider the construction of a shielded cable, the shield surrounds 
the inner conductors so Cs should be higher than Cm.  Cs being about 
2 * Cm makes sense to me and is verified by cable specifications and my 
measurements.  

If the signal common conductor is tied to the cable shield through a low 
impedance path as is often done, what is the the total cable capacitance 
as seen by the driver?  From the measurements I took with a short length 
of shielded cable with and without the signal common tied to the cable 
shield, Ct was not 3 * Cm when the shield was tied to signal common, but 
was only slightly more than Cs (about 2 * Cm).

Does anyone understand the analysis of cable capacitance given in the 
appendix of the EIA-232 and EIA-562 standards?  If you know the 
characteristics of shielded cable, what cable capacitance does the driver 
see, about 3 * Cm or about 2 * Cm as I suspect?

-- 
Joseph Perry                            Miles Inc., Elkhart, IN 46515 USA
Internet: jep@miles.com                 Voice: (219) 262-7406
UUCP: ...!uunet!miles!jep               Fax:   (219) 262-6309
--
Newsgroups: sci.electronics
From: dahls@fhydra.dnet.unit.no (Joern Yngve Dahl-Stamnes)
Subject: RE: How hot can the 486-50 cpu run ?
Reply-To: dahls@fhydra.dnet.unit.no (Joern Yngve Dahl-Stamnes)
Organization: University of Trondheim, NORWAY
Date: Tue, 18 Aug 92 09:42:53 EDT

Thus spoke the keyboard of jeremiahw@wl.aecl.ca:
>I heard that the 486 could get up to 400 deg Celcius if the appropriate program
>was run (one designed to turn on as many transistors as possible)  I am
>skeptical about the number 400 but needless to say it does run hot.  Many VARs
>and OEMs have had problems designing clones simply because of the heat problem.

At 400 deg Celcius the chip won't work very good - if it work at all.
It depend a bit of how long time the chip is at this high temperature.
I may work at 400 for a very short time, but not for any long time.

If the right program exist - it won't run very long. When the
temperature in the chip get too high, the electrical function of the
chip begin to degrade until the temperature is down to normal again.

>And the 586 is supposed to run even hotter!!  Isn't that awful?

Yes, and good cooling is even more required. When more heat is produced
in the chip, more of it must be transported away from the chip to keep
the temperature as low as possible.

+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-+
* I went back to my mother,           * Joern Yngve Dahl-Stamnes           *
* I said, "I'm crazy ma, help me!"    * University of Trondheim            *
* She said, "I know how it feels son, * The Norwegian Institute of Tech.   *
* 'cause it runs in the family."      * Division of Physical Electronics   *
*       - The Who, Quadrophenia       * e-mail: dahls@fhydra.dnet.unit.no  *
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+--+-+-+-+-+-+-+
From: efrie@yoda.eecs.wsu.edu
Newsgroups: sci.electronics
Subject: Re: Phone in use light - help!?
Summary: they complained about mine.
Keywords: phone light use light
Date: 21 Aug 92 21:23:09 GMT
Organization: Washington State University!

DO NOT BUILD THIS!
	I built one of these devices a couple years ago.  It
	consisted of a voltage  divider tap to the base of a
	2n2222 whose collector tickled another 2n2222 buffer
	to an led.  In the on hook mode it would always draw
	a few uA but in off hook mode it would steal a
	couple milliamps to run the led.

	Anyway I used it successfully for two years in one
	appartment, but after short time in my new appartment a
	GTE guy came to look for the current loss.  They
	apparently sweep the voltage to measure the
	impedance of the line to check for faults.
	I guess that explains why I would see the light come
	on for no apparent reason during my night owl study
	times.

	The tech guy told me that they complain if there
	is more than 700kohm load on the line.

	I was trying to do this without batteries but I
	guess the only answer is to build a battery powered
	1Meg input impedance comparator circuit to detect less
	than 12Volts.  Just don't use the telco's power to run
	your circuit, and make sure you keep in mind  the
	voltages of the ring and onhook.

eddie < efrie@eecs.wsu.edu >


      ______/   ___/       ___/         /    ______/
     /         /   _/     /   _/       /    /        
    ____/     /     _/   /     _/     /    ____/ 
   /         /      _/  /      _/    /    /       
  _______/   ______     ______     _/    _______/
From: mcorbin@oucsace.cs.ohiou.edu (Max Corbin)
Newsgroups: sci.electronics
Subject: Graphics Chips
Date: 21 Aug 92 16:36:54 GMT
Organization: Ohio University CS Dept,. Athens

Anyone know what graphics chips are used in tthe sega or nintendo game
systems?  If so can these be purchased?  

Anyone know of any good graphics chip capable of fast sprite movement?

Anyone know of any graphics chips worth using in some sort of video game
system?

Anyone?


-- 
+-----+---\ +-----+ 	O O 	Beware the light at the end of the
| | | | -- >|  ---+	 +	tunnel.  It may be an oncoming Dragon.
+-+-+-+---/ +-----+     \_/
   M   	 D     C	 U      mcorbin@oucsace.cs.ohiou.edu
Newsgroups: sci.electronics
From: fordke@infonode.ingr.com (Keith Ford)
Subject: Hybrid thick-film resistors
Followup-To: fordke@ingr.com
Organization: Intergraph Corporation, Huntsville, AL.
Date: Wed, 19 Aug 1992 23:13:17 GMT


There is a mathematical relationship between the area of
a thick-film resistor, the Quan-tech noise factor or the
resistive ink, and the noise index of the resistor.  I do
know that it involved logarithms, but I've confused myself
as to where they are common are natural.  Equally confusing
is the fact that decibels (dB) are dimensionless values, yet
they are used to generate an area value of some dimension.

If you can shed some light on this, please send email.
-- 
Keith Ford        __                                  73s, KA4ZDG
Intergraph Corp  /  \ Micro Magic BBS 1:373/12  Rush/Opus Archive
+1 205 730-8614  \__/ sysop@umagic.fidonet.org  server@ingr.com
fordke@ingr.com  [__] 830-2362 HST/V32bis 9600  "Subject: HELP"
From: bob@kc2wz.bubble.org (Bob Billson)
Newsgroups: sci.electronics
Subject: re: The first LED's?
Date: 15 Aug 92 19:47:29 GMT
Distribution: na
Organization: Color Computer 3: Tandy's 'game' machine

moskin@iccgcc.decnet.ab.com says:
>>From "LED Circuits and Projects", by Forrest M. Mims, III, 1973:
>
>>       In recent years, a family of semiconductor devices capable of
>>       emitting visible and infrared light has become available.
>>       Semiconductor light emission was first discovered in 1907 by
>>       H.J. Round, but it was not until 1960 that efficient light 
>>       generation in a semiconductor was obtained.
>>
>
>        I heard once that the early semiconductor diodes used in computers
>had clear casings but they were changed to opaque because they glowed red
>and alarmed people who didn't know that this was normal.  Could this be 
>considered a Light Emitting Diode?  Can anyone verify this story?

Or perhaps it was because the transistors were acting like phototransistors.

I have made phototransistors in a pinch by carefully removing the top of a 
metal cased NPN transistor (such as a 2N2222).  The exposed semiconductor
is sensitive to light.  To protect the semiconductor, I would put a drop of 
clear glue or expoy over it.  Worked out reasonably well for a couple of
situations.

      Bob
-- 
  Bob Billson, KC2WZ                          | internet: bob@kc2wz.bubble.org
                                              |           kc2wz@amsat.org
  $nail:  21 Bates Way,  Westfield, NJ 07090  | uucp:     ...!uunet!kc2wz!bob
                  C code.  C code run.  Run code run...<please!>
Newsgroups: sci.electronics
From: jeremiahw@wl.aecl.ca
Subject: RE: How hot can the 486-50 cpu run ?
Organization: AECL RESEARCH
Date: Mon, 17 Aug 1992 15:22:04 GMT

I heard that the 486 could get up to 400 deg Celcius if the appropriate program
was run (one designed to turn on as many transistors as possible)  I am
skeptical about the number 400 but needless to say it does run hot.  Many VARs
and OEMs have had problems designing clones simply because of the heat problem.

And the 586 is supposed to run even hotter!!  Isn't that awful?

>>Jerry   (jeremi@bode.ee.ualberta.ca)
Newsgroups: sci.electronics,rec.audio
From: sethb@fid.morgan.com (Seth Breidbart)
Subject: Re: CDs, Pens and Blue Lasers.
Organization: my opinions only
Date: Wed, 12 Aug 1992 21:54:13 GMT

Somebody said:

>>: > +--------------------------------------------------------------+
>>: > + The SONIC CLARITY(tm)  CORP., LTD. supports a drug-free      +
>>: > + workplace and requires that all offers of employment         +
>>: > + be contingent on satisfactory pre-employment drug test       +
>>: > + results.                                                     +
>>: > +--------------------------------------------------------------+

Many people objected to this.

"If sarcasm were posted on the net, would anybody notice?"

Seth		sethb@fid.morgan.com
Newsgroups: sci.electronics
From: drx@chinet.chi.il.us (Scott Whittle)
Subject: Re: Are Seagate Hard Drives any Good ?
Organization: Chinet - Public Access UNIX
Distribution: usa
Date: Fri, 21 Aug 1992 14:02:11 GMT

I've got a st-296N in a data logging machine. It's about a year old
and just started screaming (whining) a high pitch sound. Hasen't developed
any errors or anything. But..... Should I be concerned that this thing
may crap out on me at anytime????? I don't think a hard drive should
sound like a bad TV set with over active Horz. circuits!
s.

-- 
Scott Whittle (drx)                       drx@chinet.chi.il.us
Ground Zero Sight & Sound, inc.          
Two Wheaton Center #1111         * Ding-a-Ding-Dang my Dang-a-long-ling-long 
Wheaton, IL 60187 708.533.7471   * Ministry, JBMH, as edited by IceIce Beno
From: cpyy@vax5.cit.cornell.edu
Newsgroups: sci.electronics
Subject: IGBTs and MOSFETs
Date: 14 Aug 92 08:51:44 EDT
Distribution: sci
Organization: Cornell University

I have received a few questions about IGBTs (Insulated Gate Bipolar
Transistors) and although I have worked extensively with them in
a variety of applications, I am no expert.  I have found the
following IR applications engineer to be most helpful:

Don Dapkus
Internet: ddapkus@qed.cts.com

He has gladly answered any questions I've had about MOSFETs and
IGBTs.
-- 

Jon C. Russo
internet : cpyy@vax5.cit.cornell.edu
phone    : 607.277.3295
From: snyder@ricks.enet.dec.com (Wilson Snyder)
Newsgroups: sci.electronics
Subject: Re: 3.3 Volts (was Re: Why five ?)
Date: 12 Aug 92 16:34:02 GMT
Reply-To: snyder@ricks.enet.dec.com (Wilson Snyder)
Organization: Digital Equipment Corporation

In article <1992Aug7.012341.19932@cypress.com> you write:
> In article <1992Aug5.135506.192@crd.ge.com> kennykb@crd.ge.com writes:
|> >There's quite a move afoot to lower the standard voltage.  3.3V and
|> >2.5V are the leading contenders.  Lots of memory chips have onboard
|> >regulators and use 3.3V internally.  There's a cover story in IEEE
|> >Spectrum a couple of months ago about the proposed lower-voltage logic.
|>
|>
|> Is there anyone out there actually using, or planning to use 3.3 V
|> in the next couple of years?  I understand that there are both
|> power and speed/noise considerations.  I'm interested in what devices
|> people really want to see at this voltage level.

I am currently designing chips/systems for Digital's 21064 (Alpha)
processor.  The processor is 3.3V, although it can also support TTL
levels.  Also, the interchip bus that we are using is a true (not TTL)
3.3V bus.  Since both are 3.3V, it would be nice to have cache and
associated logic (buffers and PALs) at the same voltage.
 
Newsgroups: sci.electronics
From: boortz@sics.se (Kent Boortz)
Subject: AC zero cross detection?
Organization: Swedish Institute of Computer Science, Kista
Distribution: sci
Date: Fri, 21 Aug 1992 22:21:00 GMT


Hi,

I will interrupt a microcontroller at 220V AC zero crossing time to reset
an internal timer. Any ideas of a simple but reliable zero crossing detection
circuit? The triggering has to be isolated with a optocoupler. The 220V
will beside driving a halogen lamp be transformed down to 9V AC to drive
the processor etc. Could I detect the zero crossing point on the 9V side
or will there be a phase shift because of the induction in the transformer
and the load?

Any ideas?

Kent Boortz
boortz@sics.se
--
Kent Boortz
boortz@sics.se
From: fevrier@sunburn.ec.usf.edu. (Ian Fevrier (EE))
Newsgroups: sci.electronics
Subject: How hot can the 486-50 cpu run ?
Date: 13 Aug 92 02:29:14 GMT
Distribution: usa
Organization: Univ. of South Florida, College of Engineering




Can someone tell me just how hot the 486-50 is supposed to run. 
I just got a 486-50 with 8 mb and a 256k cache and I am a little concerned 
about the heat it generates. It gets too hot to keep a finger pressed
against the 486 chip for more than 5 seconds. Is this normal ????
Newsgroups: sci.electronics
From: adw@cci632.cci.com (Allen Williams (co-op))
Newsgroups: sci.electronics
Subject: Re: Raytel (CT scanner?) boards (for sale or dismemberment)
Date: 17 Aug 92 20:35:42 GMT
Organization: [Computer Consoles, Inc., Rochester, NY


 On extracting chips from a board, I've found that a blowtorch works
just fine. Specifically, I use the mini-blowtorch from Radio Shock, which
burns butane.

 I used this method to extract a 40 pin chip I wanted from a surplus 
PC board. It is not difficult - have a friend with a chip puller pull the
chip (gently!) as you run the flame from the blowtorch quickly but smoothly
over the solder side of the pins.

 The PC board will catch on fire and blister a bit until the solder has 
melted. This is the sign I take that the IC will soon fall out. Put the
chip aside and let it cool for an hour or so before using. The chip will
be very hot so if you pick it up right away you will be able to read the
chip numbers off your fingers. Once it's cooled, it works without any
noticeable damage. 

The disadvantages are that you trash the circuit board, so this rules out
pulling the chip to repair the board. Also, there is an acrid odor and oily
smoke that will fog the room for a while, so you should do it with the window
open, or better yet, outside. 

 I am only using a toy blowtorch, so those with metal-cutting blowtorch
rigs are left to determine their own chip extraction methods.

                                                            Derrick
Newsgroups: sci.electronics
From: mikek@iex.UUCP (Mike Keilhofer)
Subject: Where to buy parts
Organization: IEX Corporation
Distribution: dfw
Date: Fri, 21 Aug 1992 20:45:42 GMT

I'm new to DFW (live in Carrollton, work in Plano) and am
looking for electronic parts dealers. I need a dealer
with more to offer than the poor selection, low quality,
and high prices that Radio Shack offers.

I am specifically looking for analog audio chips, capacitors,
resistors, pc board transformers, rack mount cabinets etc.
to build studio equipment I design.

Can anybody help me?

Thanks in advance.

==================================================
Michael Keilhofer          
Email: [uunet!]iex!mikek or mikek@iex.com
==================================================