HDTenEightyP/NetNews huggingface dataset:
From: magnasco@research.nj.nec.com (Marcelo Magnasco)
Subject: Re: You know you've been hacking too long...
Summary: Persistence time of retina
Originator: magnasco@asterion
Organization: NEC Research Institute
Date: Tue, 18 Aug 92 22:43:26 GMT

In article <1992Aug17.073329.12346@kth.se> kjell@elixir.e.kth.se (Kjell Rilbe) writes:
>Yes! This MUST be the same phenomenon I've been talking about. You know,
>the one with floating power-indication LED on a walkman. Does anyone
>KNOW what causes this?

Different colors have different persistence times. Red is slowest. That 
trick also works with the ember of a cigarette, if you happen to smoke. 
In a very dark background, the ember seems to float out of the cigarette
as you move it around.

There is a neat demo (sold at some science museums), a kind of flat-top 
top; the flat disk at the top is painted in black and white, in concentric
circles, with some patterning for each sector (70 degrees black, then white,
etc). As you spin it, the circles `become' colored... I was told it could
be transmitted through b&w tv and still work, but I haven't seen it. 

On the other hand, what happens when you crunch stuff and look at a led 
display has to do with the strobe frequency of the leds. One of my favorite
strobe trick is to hold a straigth finger (in vertical position) to a 
fully illuminated monitor or tv (yes, that gesture), and move it very fast
horizontally while keeping it vertical. You can see distinct shadows of the
finger (because of the strobe) but if you move it really fast the shadows
are bent, leaning to one side when you move left to right and viceversa,
and that's because the strobe is not uniform (the light is swept from up
to down in each strobe).

High Regards,
Marcelo Magnasco
marcelo@mjf.rockefeller.edu	magnasco@research.nj.nec.com
Xref: sparky alt.folklore.computers:12499 comp.unix.misc:3219
From: avg@rodan.UU.NET (Vadim Antonov)
Newsgroups: alt.folklore.computers,comp.unix.misc
Subject: Re: The need for an assembler (was: Favorite CPU)
Date: 13 Aug 1992 12:58:19 -0400
Organization: Berkeley Software Design
NNTP-Posting-Host: rodan.uu.net

In article <1992Aug13.010431.4746@ecl.psu.edu> bjj@ecl.psu.edu (Bryan J. Jensen) writes:
>I have included only the subroutine which requires significant time.
>The part of concern is the 3 statements, KK = K, JJ = J, and II = I.
>Adding them, and changing function calls to use KK,JJ,II instead of
>K,J,I increased speed (by a factor of two I think).
>
> [FORTRAN code deleted]

Everybody using FORTRAN deserves to loose. This trick is well-known
for everybody who have a clue how do compilers work but it does not
justify using a language which is intrinsically inefficient and
bug-prone.

As i understand, the original discussion was about comparative merits
of using modern HLLs (namely C) and assemblers. The most attractive
feature of C is that a reasonable-quality compiler from C is quite
predictable and allows to write rather tight code while enjoying
things like portability (don't flame me, i know that there are
algorithms which tend to show quite different behaviour on
different architectures, but are they *really* so important and
ubiquotus? -- i doubt.) After all, there are things like inline
assembler and assembler itself.

The most definitive argument pro HLLs is the speed of changes in
hardware. Nowadays anybody working on a *real* project have fairly
good chances to end development on a different machine simply because
the old one became obsolete. Addiction to assembler programming
have shown its ugly side in the IBM PC world -- how do ya think
why do they hysterically keep compatibility with the crippled ten
years old machines? Ah, they *can't* change the hardware 'cause
MS-DOS will not run and Microsoft *cat't* port it 'cause it has
sufficient assembler load. Not that i like MS-DOS surviving :-)

So, being proficient in a dozen of assemblers and three dozens
of HLLs i'm still coding in C. Not that i like it but it's the most
practical language i can code in being sure that the next machine
*will* have a reasonable compiler.

Finally, if you don't like the code your compiler generates,
look for a better one (or write a better one). Not a big deal.

As for bad programmers -- a looser can write a loosing code in
any language. Ever saw ugly assembler code? I did it many times
(and what's interesting -- the worst machine code i saw usually
was in various gadgets ROMs, contrary to the wide-spread belief
that their designers have to have a clue. I think the code in such
things is usually written by electronics engineers but not
professional programmers. It's amazing how bad they can be in both
coding and user interface design ;-)

--vadim
From: msf@skaro.as.arizona.edu (Michael Fulbright)
Newsgroups: alt.folklore.computers
Subject: TV SHOW Secret Service (NBC)
Date: 17 Aug 92 01:59:15 GMT
Distribution: na
Organization: University of Arizona UNIX Users Group

NBC has a new show called 'Secret Service'.Its about cases the
organization has dealt with. One tonight was about a disgruntled
employee at a power company named Benard Posten (spelling uncertain).
This guy, which they portayed as your stereotypical computer nerd, was
fired from the power company on a charge of sexual harassment.
According to this show, he installed a 'logic bomb' in the printers at
the poer company which infected the computer(s) controlling power
distribution. His goal was to shut all power off to the city using his
virus.  Of course the good guys stopped him, but some of the stuff
they showed wass so unbelievable it made me start to wonder if they'd
made the whole thing up. They never said what city it occured at, but
it supposedly occurred in 1986. I'd really be interested if anyone has
information on this.

thanks
michael fulbright
msf@skaro.as.arizona.edu
Newsgroups: alt.folklore.computers
From: thomas@bitrot.in-berlin.de (Thomas Driemeyer)
Subject: Re: Zuse Computers
Organization: Thomas Driemeyer, Berlin
Date: Sun, 23 Aug 1992 10:07:01 GMT

In article <1992Aug19.121113.25537@public.sub.org> peterk@public.sub.org (Peter Kittel) writes:
>Yes, the Z1 was purely mechanic and did NOT work when he did it, I think
>already in the thirties. But the concept was ok, and as far as I heard
>they now built one WORKING after the old plans, for his 80th birthday
>I think.

Zuse has built a copy a few years ago. It was financed by Siemens, and is
now in the Museum fuer Verkehr und Technik here in Berlin. It is operational
but not demonstrated very often.

It consists of a large box, about 1m x 1.5m, on a table (the first
desktop machine?). It has a four-phase clock that had to be hand-cranked,
a memory unit, I/O unit, and an ALU. Bits are stored using small cylindric
pieces of metal that rest on a metal plate, and are shifted by levers
with small L- and S-shaped cutouts. These levers are arranged in rows
and columns; you address a row of bits and then change the bits by moving
the column levers, during the right clock phase. If I remember correctly,
it can store 64 words. The ALU, especially the multiplier, is insanely
complex.

The text said it was infinitely more difficult to build the original
machine because all the levers (except clocks and a few others) are flat
strips of metal with complicated cutouts, and if the cutouts aren't
perfectly smooth the levels would get stuck easily. The replica was
built using erosion cutting techniques.

It is pretty amazing how much the machine resembles a modern von-Neumann
computer. Don't ask me about MIPS (actually, IPS) though. The museum also
has an original Zuse flatbed plotter (Z-64) and various other peripherals
and external memory devices.

Thomas
-- 

--
Thomas Driemeyer      thomas@bitrot.in-berlin.de      voice/fax: +49 30 8924936
Newsgroups: alt.folklore.computers,comp.unix.misc
From: rbe@yrloc.ipsa.reuter.COM (Robert Bernecky)
Subject: Re: The need for an assembler (was: Favorite CPU)
Reply-To: rbe@yrloc.ipsa.reuter.COM (Robert Bernecky)
Organization: Snake Island Research Inc, Toronto
Date: Sat, 15 Aug 92 21:54:27 GMT

In article <1992Aug14.085002.10857@news.columbia.edu> lasner@watsun.cc.columbia.edu (Charles Lasner) writes:
>In article <1992Aug12.233613.4745@ecl.psu.edu> bjj@ecl.psu.edu (Bryan J. Jensen) writes:
>
>Microsoft MASM as an assembler sucks rotten eggs.  All assembly programmers
>I know who cut their teeth in a variety of other places have one thing in
>common: they loathe and despise virtually everything about Microsoft from
>its business inception to its products to its policies, etc. and mostly
>they hate MASM.  If they do use an 80x86, they use Borland products, including
>C++ pro and TASM.  Microsoft C is incompatible with everything but its own

Mostly, I don't like their products, which are expensive, and too slow
and ill-designed for my taste. However, you is made a big booboo
up above. It ain't rotten eggs; it's dead bears.
>Perhaps people should get paid not by the line of code, but rather by the
>count of comments in it.  Since assembly language offers more opportunity
>for more types of comments at various lower levels, this would encourage
>quality.  You will tend to see line-by-line comments on the right, and
>also section descriptions for better-grade code.  Well-written macroes can
>generate comments for you that actually can be somewhat useful.  (Again, the
>macro construct as a good assembler will encourage you to do is such a wasted
>resource :-(.)

Machine lifetimes are too short to code in assembler, unless your 
application is the lifeline of some company, in which case assembler makes
for good job security.

As for getting paid by the line of code: This is the wrong way to 
approach it: Code maintenance costs are proportional to code volume.
I'll pay my programmers per line of non-code: The shorter, the better.
Consider these advantages:

a. Non-code can't have any bugs in it.
b. Non-code can't be optimized any better than it is already. It runs
   in zero time.
c. Non-code does not have to be understood by someone new to the
   application.




Robert Bernecky      rbe@yrloc.ipsa.reuter.com  bernecky@itrchq.itrc.on.ca 
Snake Island Research Inc  (416) 368-6944   FAX: (416) 360-4694 
18 Fifth Street, Ward's Island
Toronto, Ontario M5J 2B9 
Canada
Newsgroups: alt.folklore.computers
From: zcookbruc@cc.curtin.edu.au
Subject: Re: pdp-11 -> mac network?
Organization: Curtin University of Technology
Date: Thu, 20 Aug 1992 10:52:57 GMT

In article <1992Aug19.215618.14550@vax5.cit.cornell.edu>, cc2x@vax5.cit.cornell.edu writes:
>    Is there a program out there that allows macs and pdp-11s to network
> together. We are putting together a small appletalk network and want to
> put our pdp-11 in there too.
>   Could one mac act like a gateway and pass data from one serial port to
> an other thus getting the data on the network?
>   Thanks
>    -Jeff
> 

One off-the-shelf (DEC) solution would be to get a small VAX
(lunchbox 2000) maybe and use that as a bridge using MAC PATHWORKS
and DECNET to the '11

Have a look at MAC pathworks, you may find it contains DECNET and
therfore a ready-made solution.

...BRU
Xref: sparky alt.folklore.computers:12479 comp.unix.misc:3216
From: cbbrowne@csi.uottawa.ca (Christopher Browne)
Subject: Re: Bogosort
Organization: Dept. of Computer Science, University of Ottawa
Date: Fri, 14 Aug 92 03:25:08 GMT

In article <fstuart.920813191644@lab16.eng.auburn.edu> fstuart@eng.auburn.edu (Frank Stuart) writes:
>Isn't there a provably best (or at least better than most) algorithm out there
>that no one uses because when you go to implement it, the constants overwhelm
>it?

(1) Strassen (sp?) transformations to speed up matrix multiplication from
O(n^3) to O(n^2.37...) (2.37 might be some slightly different number!)

The constant factor out front is big enough that you need to be talking about
simply ENORMOUS and DENSE matrices in order to make it worthwhile (something
like 1500x1500).

Of course, with sufficiently large problems, it WILL be worth using....

(2) Ellipsoid method of Linear Programming.
This got published in Byte and Time, and was supposed to be the greatest
thing since sliced bread.  The classical simplex method can take exponential
time, compared to polynomial time for the Ellipsoid.  Unfortunately, in
finite precision math, it bogs down, produces very dense matrices (out of
stuff that might start out sparse), and is useful only in theory.

The more recent "interior point" methods (Karmarkar being the notable one
to start the literature) are also polynomial, and have a large enough
constant that the simplex method is faster for small/medium scale problems.
In 5 more years, "small" problems will be large enough that interior methods
will likely control the market...
-- 
Christopher Browne
cbbrowne@csi.uottawa.ca
University of Ottawa
Master of System Science Program
From: sandee@Think.COM (Daan Sandee)
Newsgroups: alt.folklore.computers
Subject: Re: Deutsches Museum (was: Zuse Computers
Date: 22 Aug 1992 21:41:34 GMT
Organization: TMC
Distribution: world
NNTP-Posting-Host: telecaster.think.com

In article <1992Aug21.072019.14385@grmbl.saar.de>, me@grmbl.saar.de (Martin Emmerich) writes:
|> In <4058@cruzio.santa-cruz.ca.us> aki@cruzio.santa-cruz.ca.us writes:
|> 
|> >In article <1992Aug16.200705.58190@cc.usu.edu>, ivie@cc.usu.edu (CP/M lives!) writes:
|> >> It was kind of funny seeing people try to take flash pictures of the
|> >> planetarium screen...
|> >Will those tourists _EVER_ learn?
|> 
|> I once visited the Peter's Church in Rome, the biggest church in
|> Christianity. You can see the tourists standing there, trying to
|> lighten the really huge dome with the flash of their pocket cameras.

Aw, come on. I can beat that easily. I've seen people take flash pictures
of the sunset.

Daan Sandee                                           sandee@think.com
Thinking Machines Corporation
Cambridge, Mass 02142                                 (617) 234-5044
Newsgroups: alt.folklore.computers,comp.unix.misc
From: davgot@auto-trol.com (David Gottner)
Subject: Re: The need for an assembler (was: Favorite CPU)
Organization: Auto-trol Technology Corporation
Date: Wed, 19 Aug 1992 16:08:44 GMT

In article <bqt.714224577@Minsk> bqt@Minsk.docs.uu.se (Johnny Billquist) writes:
>In <repo.037m@depo.UUCP> repo@depo.UUCP (repo man) writes:
>
>How can you tell, when you don't even know what code it generates?
>I suppose you've been listening to "people_who_know" who says so.
>
Have you heard of assembly listing options, and disassemblers?

>I can accept that some people doesn't like assembly language, that's ok.
>I can also accept that hll programmers are just as adept as assembly
>programmers. I cannot accept that a compiler would be smarter than a
>programmer. If you put more abstractions between you and the machine,
>you will have to accept that you get less control over what really happens.
>

I have complete control of the hardware with some HLL's (like C).  If I want
a left shift I use '<<'.  If I want a signed multiply I use '*' on two signed
numbers.  What more control could I want?

I suppose that there are >>some<< limitations.  You can't write interrupt
routines with standard C, but that is what assembler is for.  However, C
gives you so much control that assembly is rarely necessary.


>Oh yeah? How does the compiler know exactly what you want? Does it ask
>you 101 questions, or does it read your mind?
>Face it once and for all. Compilers don't know what you want, so they
>do exactly what you say, and hopes you know what you want.
>It's often not easy to do things optimally in this way, but it has
>a fair chance of working.
>

Does your assembler know exactly what you want?  Does your assembler ask you
101 questions or does it read your mind.  Face it once and for all.  Assemblers
don't know what you want, so they do exactly what you say, and hopes you know
what you want.

>Nope, you don't need to know how a microwave oven works to heat
>a chees burger. To call this cheesburger perfect is a lie every
>day though.

Everything is perfect.


>--
>Johnny Billquist                  || "I'm on a bus
>CS student at Uppsala University  ||  on a psychedelic trip
>email: bqt@minsk.docs.uu.se       ||  Reading murder books
>pdp is alive!                     ||  tryin' to stay hip" - B. Idol


-- 
Amrit Prem			|
davgot@auto-trol.com		| This area is intentionally left blank
{...}ncar!ico!auto-trol!younam 	|
From: ahm@spatula.rent.com (Andreas Meyer)
Newsgroups: alt.folklore.computers
Subject: Re: Pick -- what is it?
Date: 16 Aug 92 05:54:17 GMT
Reply-To: ahm@spatula.rent.com (Andreas Meyer)
Organization: The No Exit Cafe and Health Food Emporium

zrepachol@cc.curtin.edu.au (Paul Repacholi) writes:
> Why is there no "R" in Pick?
> Because then it would be usefull.
> Primos doesn't even have that advantage... :-)

...but it DOES have an "R" in it...  B^)

Andy
Newsgroups: alt.folklore.computers
From: zrepachol@cc.curtin.edu.au (Paul Repacholi)
Subject: Re: Favorite REFRESH
Followup-To: alt.folklore.computers
Organization: Curtin University of Technology
Date: Sat, 15 Aug 1992 16:15:02 GMT

In article <13890@auspex-gw.auspex.com>, guy@Auspex.COM (Guy Harris) writes:
> (Followups again redirected to "alt.folklore.computers")
> 
>>The MARK instruction on the PDP-11 I't rumoured that Dave Cutler used
>>it once in the RSX exec, just so that the instruction wasn't wasted.
>>
>>I think this instruction saw the light of day in the T-11 chipset
> 
> Saw the light of day, or *disappeared*?
> 
> MARK long antedated any of the microprocessor PDP-11s; I think it first
> showed up in the 11/45, although not all subsequent PDP-11s had it (as I
> remember, it wasn't in the 11/40, for example).

Yes, first in the KB-11 CPUs. It is NOT used in RSX, though there is a spot
where it could be. RSTS/E uses it I believe. 
Also in the KDJ cpus and I think, the 11/60, and 11/44.

~Paul
From: grog@adagio.UUCP (Greg Lehey)
Newsgroups: alt.folklore.computers
Subject: Re: Good source code to read?
Date: 12 Aug 92 12:13:28 GMT
Organization: LEMIS, Schellnhausen 2, W-6324 Feldatal, Germany

In article <BsHq2L.GGL@zorch.SF-Bay.ORG> phil@zorch.SF-Bay.ORG (Phil Gustafson) writes:
>Well, if your site has a UN*X source license, take a look at the /bin/sh
>code, by Steve Bourne.

Don't do it! If AT&T has its way, this could seriously impair your
choice of jobs in the future (see their suit against BSDI, UCB and all
-- 
Greg Lehey                       | Tel: +49-6637-1488              
LEMIS                            | Fax: +49-6637-1489
Schellnhausen 2, W-6324 Feldatal, Germany
*** NOTE ***: Headers are mangled - reply to grog%lemis@Germany.EU.net
Newsgroups: alt.folklore.computers,alt.3d
From: lasner@watsun.cc.columbia.edu (Charles Lasner)
Subject: Re: 'Movement' on light and dark screen background.
Reply-To: lasner@watsun.cc.columbia.edu (Charles Lasner)
Organization: Columbia University
Date: Sun, 16 Aug 1992 18:41:46 GMT

In article <1992Aug16.091444.1401@spatula.rent.com> ahm@spatula.rent.com (Andreas Meyer) writes:
>sauron@nano.engr.mun.ca (Patrick Ryan) writes:
>> hsu@pix.com (Dagwood Splits the Atom) writes:
>> 
>> >Now, if only they'd do a commercial with SIRDS.  Fat chance.
>> 
>>  Sorry if this is a FAQ, but what's SIRDS?
>
>"It's a candy mint... it's a breath mint..." :-)

I thought it's a floor wax AND a desert topping; it's two, two, two products
in one.

cjl (also Live from New York)

Newsgroups: alt.folklore.computers
From: phz@cadence.com (Pete Zakel)
Subject: Re: Peet Peeves! (was Re: pronouncing "bps"?)
Organization: Cadence Design Systems
Date: Thu, 20 Aug 1992 19:47:03 GMT

In article <Bswn7H.9ro@pix.com> hsu@pix.com (Big Dave Hsu) writes:
>Observe the Philips CompactCassette
>logo on each of your audio cassettes (yes, it's molded into the shell
>somewhere)...ever wonder what a full-sized cassette looked like?

Wonder no more.  A full-sized cassette is an 8-track tape cassette.
Remember those?

-Pete Zakel
 (phz@cadence.com or ..!uunet!cadence!phz)

"A witty saying proves nothing."
		-- Voltaire
Newsgroups: alt.folklore.computers
From: magnus@thep.lu.se (Magnus Olsson)
Subject: Re: Bogosort
Organization: Theoretical Physics, Lund University, Sweden
Date: Fri, 14 Aug 1992 11:44:04 GMT

In article <1992Aug14.095724.26168@mullet.gu.uwa.edu.au> john@mullet.gu.uwa.edu.au (John West) writes:

>Of course, when you're best case is O(n!), as one algorithm I've recieved...

Oh, that's easy: Just modify bogosort slightly:


Input: N real numbers
for all permutations of input do begin
    if current permutation is sorted then
         print it out
end

Or perhaps your algorithm is more refined? :-)


Speaking of amazingly bad algorithms, one thing that amazes me is how
often people who've seen a little linear algebra use Cramer's rule to
solve systems of linear equations. 

Cramer's rule is an explicit formula for the inverse of an NxN matrix.
It involves computing the determinants of all the matrices you get by
deleting a row and a column from the original matrix. 

So, given the system Ax = y (where A is an NxN matrix and x and y are
N-vectors), these bozos first compute A^-1 by Cramer's rule, and then
compute x = A^-1y. Sure, it works, but it's about the slowest possible
way any sane person could imagine to solve the equations (of course,
insane persons can come up with the linear algebra equivalent of a
bogosort :-) ). 

I remember seeing one such program back when I was in high school - it
was written in Basic and ran on an ABC 80. It was pretty impressive to
a high-school kid; it actually solved 7x7 systems in a few seconds. I
was less impressed when I found that it needed a minute on 8x8 systems
and several hours on 9x9...


Footnote: You may wonder why they bother teaching this method at all.
In fact, it's a valuable theoretical result - an explicit, closed
formula for the inverse of a matrix, and pure mathematicians are more
interested in that than in actually _solving_ anything. (Of course,
any maths prof worth his/her salt would teach Gaussian elimination as
well. But students tend to like explicit formulas better, because they
can be implemented without any need for thought). 

Magnus Olsson                   | \e+      /_
Dept. of Theoretical Physics    |  \  Z   / q
University of Lund, Sweden      |   >----<           
Internet: magnus@thep.lu.se     |  /      \===== g
Bitnet: THEPMO@SELDC52          | /e-      \q
From: ddb@tdkt.kksys.com (David Dyer-Bennet)
Sender: FredGate@tdkt.kksys.com
Newsgroups: alt.folklore.computers
Subject: Non Unix-os's
Date: Tue, 18 Aug 1992 11:15:04 -0600

I like your comparison list; so you're suggesting that IBM displaced
Osborne because they had the forsight to provide a cassette port? :-)
:-) :-)

 TB> So although IBM might have come up with a different implementation, it
 TB> wasn't better.  Remember CP/M 3.0 can deal with 1.0 Megabytes of
 TB> memory, and DOS (all versions) can only deal with 640K.  

This turns out not to be the case (the part about DOS).  The DEC
Rainbow, for example, could run MS-DOS with 896K of memory.  (Yes,
this is a nit).

 * Origin: There'll be enough to go around (1:282/341.0)
From: jbickers@templar.actrix.gen.nz (John Bickers)
Newsgroups: alt.folklore.computers
Subject: Re: The need for an assembler (was: Favorite CPU)
Date: 17 Aug 92 09:33:31 GMT
 <1992Aug14.081326.24359@news.columbia.edu> <id.NZDS.UCE@ferranti.com> <1992Aug16.074623.2955@news.columbia.edu>
Organization: TAP, NZAmigaUG

Quoted from <1992Aug16.074623.2955@news.columbia.edu> by lasner@watsun.cc.columbia.edu (Charles Lasner):

> the people whose names you used, then you are proving my point:  There are
> possibly as few as 5 people who actually have a clue as to what a compiler

    Gee, this is a bald-faced lie. The majority of C compilers I've
    ever used (and I'm just a beginner) have got object module
    disassemblers, which I've made use of.

> cjl
--
*** John Bickers, TAP, NZAmigaUG.        jbickers@templar.actrix.gen.nz ***
***    "Radioactivity - It's in the air, for you and me" - Kraftwerk    ***
Newsgroups: alt.folklore.computers