At 22:18 -0600 11/15/06, Sridhar wrote:
>90 degrees south always points to the South Pole. It doesn't always
>point to the same place, though. The precession of the Earth's
>rotational axis causes the location of all coordinates on the Earth's
>surface to shift by a small amount all the time. It's most easily
>noticed at the poles. Barring smaller corrections of much shorter
>period and magnitude, the Earth's axial precession occurs on a period of
>about 26,000 years.
All true, but partially unconnected and somewhat
oversimplified. Earth's angular momentum vector precesses about the
normal to the ecliptic (the plane of Earth's orbit) in a cone with
half-angle 23.5 (or so) degrees and with a period of 26,000 years.
This is directly driven by the lunar and solar tidal torque on the
equatorial bulge of the Earth, which is in turn caused by the Earth's
rotation. For a rigid body, this could happen without any change in
the location of the "pole" as seen on the surface of the body.
Independent of that (or of any external torque), the point at
which the Earth's angular velocity (not momentum) vector intersects
the surface, which is the instantaneous pole, wanders around on the
surface. This is due to several things. One is the fact that the
angular momentum and angular velocity may not be perfectly aligned.
(Even a rigid body will do this if it is not spun along either its
major or minor principle axis of inertia. This is the "polhode"
motion of a freely rotating body as seen from the body.) Another is
the fact that the Earth is continually rearranging its mass
distribution by rainfall, earthquakes, ice-sheet melting, etc. etc.,
thus moving its principle axes of inertia around and causing the
first condition to apply. (These mass redistributions are in turn
driven primarily by the effects of incoming solar radiation, but this
is an indirect effect of the sun on the system.) Another cause is due
to the fact that the "solid" Earth is really a composite system, with
many different solid and liquid components, many of which may be
rotating with respect to one another and causing various interactions.
I think I will stop there, acknowledging that I'm still
oversimplifying.
I will however add that I at one point in the early 1980's
wrote a program in Fortran on a PDP-11 to display the current and
predicted (by the IERS) Earth instantaneous pole coordinates on a
Tektronix 4025 graphics terminal, erasing and re-drawing the
predicted pole with every new update of the current pole. It was
interesting to see how consistently off the predictions were.
Sorry for the delayed-gratification nature of this post; I'm
just getting back from 2 weeks' vacation.
--
Mark Tapley, Dwarf Engineer
(I haven't cleared my neighborhood)
210-379-4635 Dwarf Phone, 210-522-6025 Office Phone
someone set me strait if Im way off - is an emulator,
like MAME in essence a parser essentially? I bet
theres probably more to it then that though...
--- cctalk-bounces at classiccmp.org
<mbbrutman-cctalk at brutman.com> wrote:
>
> On the old standup arcade games multiple CPUs are
common.
>
> Williams Defender uses two 6809 CPUs - one just for
sound, and one for
> everything else.
>
> Williams Joust is more complicated and uses four
6809s.
>
>
>
> Mike
>
____________________________________________________________________________________
Do you Yahoo!?
Everyone is raving about the all-new Yahoo! Mail beta.
http://new.mail.yahoo.com
Has anyone attempted to make a "big picture" view of the vendor
landscape by creating a chart showing spin-offs and acquisitions of
various vendors?
I find this information sprinkled throughout Wikipedia, but no
attempt at creating a "big picture" view.
Has anyone done such a thing?
--
"The Direct3D Graphics Pipeline" -- DirectX 9 draft available for download
<http://www.xmission.com/~legalize/book/download/index.html>
Legalize Adulthood! <http://blogs.xmission.com/legalize/>
--- Jim Leonard <trixter at oldskool.org> wrote:
> arcarlini at iee.org wrote:
> >>> How about the Sega MegaDrive/Genesis? That ran
a
> 68000 and Z80.
>
> There have been many multi-cpu consoles; the Sega
> Saturn had two Hitachi
> RISC CPUs for core processing, plus a host of othe
r
> stuff for CDROM,
> display, sound... The PlayStation 2 is also
> dual-CPU. The PlayStation 3
> is a Cell monster, 7 cores you can play with,
wrong!!! Some places state 9, but the last
*official* CPU diagram I saw has 8 cores.
One main core (slightly larger than the others)
and 7 co-cores. (Does that make sense?)
> although I think that's
> been discussed here already by Mr. Brutman.
>
> My favorite was the Atari Jaguar, which had no les
s
> than:
>
> - a 32-bit RISC GPU
> - a 64-bit RISC "object processor"
> - a 64-bit RISC blitter
> - a 64-bit general purpose DSP for audio and other
> functions
> - a 68000 for general-purpose helper functions
>
> And to shuffle memory around, a 64-bit DRAM
> controller.
>
> The Atari Jaguar *should* have been the most
> kick-ass console of its
> generation (the blitter in particular was certainl
y
> the most powerful of
> all the 5th-generation consoles). But it was so
> complex that nobody
> could figure out how to program it properly.
> Coupled with legendary
> Atari marketing fumbles, it died a quick death
> before a suitable "killer
> app" could be developed for it.
>
> Most coders unfamiliar with the system would treat
> the Jaguar as a
> 68000-based machine with a giant framebuffer, like
> an Atari ST on
> steroids. This was clearly not the best use of th
e
> machine.
The Atari Jaguar is basically a Super Spectrum
(SS).
No I'm not kidding (surely someone here can
back me up?). There is a page on the web
somewhere explaining how the guys that were
designing the SS ended up working for Atari.
The SS evolved into the Atari Jaguar.
Also, with the CD unit fitted into the Jaguar
cartridge slot (so it could play Jaguar CD
games - of which there must be about 6!)
that add's yet another processor or two
possibly.
Regards,
Andrew B
aliensrcooluk at yahoo.co.uk
All:
Here's an interesting one. I have several disk images for the
Tandy 2000 that had been made with TeleDisk. One of the images is bad for
some reason (must be truncated; won't get past track 30; complains that
target disk drive is not ready when it reaches T30). The original disk is
not available.
I've done the basic troubleshooting on the drive and media
(other images made with same new floppy diskette and drive work fine;
swapped drive and media) to eliminate them from the failure tree.
Even though TeleDisk seems to write to track 30 just fine, the
disk is unusable. This is odd because it's an MS-DOS format (although 80T
9S) so all of the directory and media parameter info is at the front of the
disk rather than the back.
Is there anything I can do with this partial disk image to
retrieve at least some of the info?
Rich
Rich Cini
Collector of classic computers
Lead engineer, Altair32 Emulator
Web site: <http://highgate.comm.sfu.ca/~rcini/classiccmp/>
http://highgate.comm.sfu.ca/~rcini/classiccmp/
Web site: http://www.altair32.com/
/***************************************************/
Hey, all,
I put together this list from the "Green Goo" thread. If anyone has
more good information about various cleaners, or procurement information
about ones listed, I would appreciate hearing about it, and I'll update
the list. It could be handy -- maybe even a FAQ answer.
Sincerely,
Warren Wolfe
**********************************************************
Gentle Cleaners Used on Old Computers.
Caig DeOxIt - Remove oxidation from electronics, and clean
- http://www.tubesandmore.com/
Caig ProGold - Seal and lube circuit card edge fingers, etc.
- Radio Shack 64.4338
http://www.tubesandmore.com/
GooGone - Cleans off old adhesive residue.
Mr. Clean - Cleans stains, discoloration, and magic
marker from painted metal.
Magic Eraser
Afta - Cleans glues and residues
- Home Depot
CaiLube MCL - Cleans and lubes potentiometers, especially.
-
http://store.caig.com/s.nl/sc.2/category.183/.f
This just in: we picked Saturday, June 9, and (probably) Sunday, June 10 as
well. Hopefully we will determine the need for a second day soon.
Someone, somewhere, will probably have a graduation-related conflict. To
that person(s), I apologize, but we did our best.
East 3.0 was awesome, but I gaurantee that East 4.0 will kick 3's ass!!
- Evan
Kind of neat:
http://www.msnbc.msn.com/id/15984363/
Rob
Robert Borsuk
irisworld at mac.com
--
(\__/)
(='.'=) This is Bunny. Copy and paste bunny into your
(")_(") signature to help him gain world domination.
Gordon JC Pearce wrote:
> No, but it does have an EPROM in the extension socket labelled "TOOLKIT
> ROM #A000" or something similar. I've never quite figured that one out.
>
>
Maybee this Atom toolkit:
http://www.xs4all.nl/~fjkraan/comp/atom/toolkit.txt
Fred Jan
