> Just imagine flying across the country and in mid flight having to shut
> everything down and re-booting or even worse having to reload the airplane
> in mid flight.
Ask the US Navy about this... who had a WinNT system die on a ship, and
had to be towed back to port because they couldn't get it running again.
<http://www.gcn.com/17_17/news/33727-1.html>
-chris
<http://www.mythtech.net>
Hi,
does anyone know of an on-line manual for a M873 YB loader? I can find a few
diagrams (hard copy) at work, but none of the associated documentation or
listings (or what the installed loaders do).
Thanks
Jim.
Please see our website the " Vintage Communication Pages" at WWW.G1JBG.CO.UK
Hi
He might check out the circuit breaker. These
are know to go bad, especially if they are used
often as a switch or have been tripped often.
Unless there is a soft start circuit, it is
unlikely that the filter capacitor would trip
the breaker but otherwise continue to work after
the power came up normally.
Dwight
>From: "Wai-Sun Chia" <waisun.chia at gmail.com>
>
>On 4/19/05, Steven_R_Hutchins at raytheon.com
><Steven_R_Hutchins at raytheon.com> wrote:
>>
>>
>> I am considering using two modern +5v at 25A switching power supplies to
>> replace the +5V source ( leaving the original -5V at 2A,+15 at 2A,-15 at 2A,and
>> +20 at 4A as original) in a PDP-8A.
>> My intent is to increase the reliability of the system. I have had trouble
>> with keeping the G8018's operating. I occasionally trip the breakers on
>> startup. I am thinking bad filter Caps. Perhaps someone could give some
>> opinions on this (Crazy) idea.
>
>Hmm....here's a crazy thought..
>What about...replacing the filter caps? :-)
>Or troubleshooting the PSU?
>
>A PDP8 with a SMPS to me is total heresy.
>Where do you stop?
>
>One of the tenets in classic computing (to me anyway) is to retain
>originality as far as possible or as much as your funding/SO permits..
>:-)
>
>/wai-sun
>
>
In 1999, I went to work for Philips, managing customer support for CD
burners and DVD burners.
State of the art then was 2X, going to 4X. There were very few
suppliers of RW media or burners; Sony had the biggest market share but
exited quickly to free up capacity for the PlayStation 2.
Philips had a large lab in Hasselt, Belgium. One section was to test
all media in the marketplace to see that it was within spec, would work
on the Philips' drives. And most importantly, that it was legal; ie
paid the license fees to the patent owners - Philips, Sony, HP etc.
CD-R and CD-RW fees are a huge source of income. And that little logo on
the doors of drives also means that they paid the fees, another large
source of revenue. This IP is agressively enforced.
The test lab was fascinating. They went through thousands of disks a
month. Various offices of Philips around the world would buy the media
and send it in for testing and fee verification. Hong Kong, Taipei, and
Seoul all sent in big boxes every month.
There were many tools used to verify the p[hysical parameters and the
electrical. They even had a calibrated dust machine to test door seals
and dust read through. It was literally a chamber that would be filled
with different particle sizes of fine dust for hours on end.
I also got to visit the R&D lab in Eindhoven, where the original work on
CDs took place. The still have the original CD that was the first to be
read. And it can still be read.
All of this leads up to some of the information being tossed out on this
thread. I'll try to put down what I know.
1. There are very few high volume suppliers in the world of good tight
tolerance polycarbonate disks. They have a huge investment in automated
manufacturing equipment. Just like ICs makers, the start up costs
prevent most companies from entering the market.
2. Thus, most CD-Rs and DVD+/-Rs come from a small number of physical
plants. In 2000, you could count them on one hand. Since then, they
may have doubled.
3. The major differences in media came from the dye and the process to
deposit the dye. Many companies (such as Philips, HP, Memorex, TDK)
have a propietory dye they have developed themselves. They contract out
the manufacturing of the actual disks. As with any outsourcing, some
companies may have multiple sources for the same part number.
4. Getting these processes under control takes time. The quality of
parts made this year is orders of magnitude better than it was in 2000
and 2001. If you are making decisions based on media purchased a few
years ago, your data points don't reflect what is out there today.
This is one of the reasons for the varied experiences on the same media.
The factories could be different, the processes better, the formula
changed. But the brand and model number could be the same.
5. Saying a certain brand is crap, and another outstanding may be only
a personal bias. For example, in the ealy days of DVD+RW disks, I
visited the factory that Philips used for their brand name. In the same
building, I saw production lines for the other 5 companies shipping
DVD+RW at that time. In other words, it all came from the same factory!
A couple of days later, I was in CompUSA and salesman lectured me on
how one brand was so bad they didn't carry it any more; but Brand X
really had their act together. Both brands literally came from the same
line and dye process - they were under a cross licensing agreement.
6. There CAN be very real differences of user experiences. But media
is not the only factor, not even the biggest factor. Just like magnetic
media, these are complex systems of media, read/write channels,OPU
construction, chip sets, software and firmware.
7. Lasers are an exception. There were only 2 laser sources in 2000
for CD-R devices. They used the Seagate "waterfall" priciple: the
tightest spec parts went to the biggest buyer or payer of the best
prices. Further down, parts with wider specs went to the next tier of
OEMs. Finally at the bottom, what's left went to the companies you
never heard of - they don't sell in the US marketplace for obvious reasons.
The lasers go into OPUs (Optical Pick Up Units). There are again only
a handful of OPU suppliers in the world. For a long time, if you bought
a CD-R drive, the OPU came from one of two companies, regardless of the
brand of the drive. Today 3 companies still have most of the market.
8. Another factor being ignored in this dicussion is the progress made
in improving reliability. The CD recordable market went from 2X to 52X
in around 3 years. Depending on how you count, that was 10 or 11
generations. Entire new chip sets and suppliers suddenly appeared,
leveraging of the previous generations. New features were added. The
firmware solved the over/under run problems, then the tracking at higher
RPM, then the read through scratches, thermal compensation for thinner
dye etc. Recently, the first SATA drives showed up.
Unless you buy new drives every six months, your experience on a given
drive and media can be radically different from somebody else with the
same combination but newer/older than you.
9. After being involved with tens of thousands of disks burned, I have
data that shows very little difference in performance from one type of
media over another. There ARE some really crappy disks coming out of
China - I've seen some I could read a newspaper through. Another
factory ships everything pre-scratched. But with rare exceptions, these
disks never reach the US or Europe.
If you have personal preferences that lead you to pick one brand over
another, go with it, But base your decision on the results of YOUR
drive with YOUR media. If you run into a nay-sayer for a particular
type, ask for his data - what drive, what media etc. The hits being
given to certain suppliers or factories are probably not based on large
scale testing on multiple drives. Some of these opinions don't sound
like they are based on data at all.
The current quality and state of the art at some of the companies being
run down in this forum are excellent. It is probably 90-10 a drive or
software problem rather than a media issue. Make your decisions on your
data, not someone else's bias.
Billy
Just a short post to introduce myself and what I'm up to...
I'm currently looking into one of Intergraph's old InterPro systems (a 2830)
and trying to dig up enough documentation to allow me to ultimately port
NetBSD to the box to replace the native CLIX (an old SYSV 3.2ish Unix).
Have made some pretty good progress on disassembling the boot EPROM and
writing the beginnings of a hardware simulator. After discovering the
CLIPPER CPU book online (not to mention the DP8510 BitBlt unit databook!), I
think my off-the-shelf chip documents are almost complete. Information on
the custom ASICs is almost nonexistent, but the system diagnostics provide
some good reference code which should provide useful information.
I'm curious to know if there's anyone else out there that's interested in
these relatively rare boxes? For anyone that cares, the basic hardware in
the box is:
C4M CLIPPER CPU at 70MHz, ECC RAM
Zilog 85C30 SCC and 85230 ESCC - one port used by keyboard, other three
available
Xilinix XC3020 fpga controls Versatec, Centronics or Intergraph
compatible plotter interface
Intel 82596 ethernet controller
NCR53c94 SCSI host controller
NEC82077 floppy controller
Dallas DS12887 RTC and NVRAM
128k boot UV EPROM
2x128k diagnostic/boot flash EPROM
The graphics board is built up with:
DP8510 BitBlt unit (x2 on dual head board)
custom Bresenham line-drawing ASIC
bt459 DAC (x2 on dual head board)
2x1M VRAM (double buffered), (x2 on dual head board)
The real key to the missing documentation is the remaining IOGA and SGA
custom asics on the system board. Anyone who has any other documentation on
this stuff would be a friend for life ;).
Regards,
Pat Mackinlay.
Help,
My Quantum DL4000 or DEC TZ88 has come undone...
IOW, the leader which snares the tape has come loose, and I don't know
how to wind it back... :-{
The mechanism has 6 heads; I tried to wind it around the 6-headed
path, but the leader is not long enough, so it must be wound around a
shorter path...but which one??
It's OK it nobody's understand what I'm talking about :-), as long as
someone is kind enough to post naked pics of a working TZ87/88 of how
the leader is being wound.
TIA.
/wai-sun
With regard to DVD-R media, FWIW, I've had surprising and unexpected
consistently high quality performance with the "K-Hypermedia" DVD-R media
sold by OfficeMax (on very few occasions, I've seen this brand at other
retailers, but mostly at OfficeMax). I expected this to be a cheap
off-brand, but I've been using it for almost 3 years now, hundreds of
pieces, on several different burners, and I've had consistently excellent
results (including, so far, good data retention and readability as much as
2-3 years later). And it's relatively cheap when it's on sale (often). And
I've had a few other people who are more than casually into optical media
(people formerly associated with Roxio) report the same finding on this
brand. Note, this applies only to the Blue silk-screen DVD-R media, 1x, 2x
and 4x. They make (or should I say sell) other media, both DVD+ and CD, but
I've had no experience with any of the other types.
On Apr 19 2005, 21:19, Wai-Sun Chia wrote:
> We're WAY past that milestone... :-)
>
> On 4/19/05, Fred Cisin <cisin at xenosoft.com> wrote:
> > We all must do whatever it takes to make Bill Gates into a
millionaire.
I have a feeling Fred was thinking of reductions, not increases :-)
--
Pete Peter Turnbull
Network Manager
University of York
