Verifying Chip Capacitors

That is about as stupid a remark as I have seen you make in a long time.

It also proves that you have barely even a cursory grasp of spreadsheets in general, including ALL versions of excel.

Especially the more recent releases.

You could not be farther from iterating facts if you were actually trying to.

Reply to
CellShocked
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Guilty! I never use Excel unless somebody sends me a spreadsheet and I absolutely can't avoid opening it. Yucch. It's almost as brain damaged as PowerPoint.

Actually, I usually let somebody else open spreadsheets for me, and print them out.

Some of my customers *think* in Excel and PowerPoint, and it shows... their thinking is seriously constrained, like living in a cartoon world. Excel and PP seem to destroy peoples' ability to think and write clearly.

It's funny how many people are described as "tech savvy" these days. That means they can use Excel and Facebook and punch buttons on their smart phones. Not

0.1% of them have any idea how a computer works.
--

John Larkin                  Highland Technology Inc 
www.highlandtechnology.com   jlarkin at highlandtechnology dot com    

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom timing and laser controllers 
Photonics and fiberoptic TTL data links 
VME  analog, thermocouple, LVDT, synchro, tachometer 
Multichannel arbitrary waveform generators
Reply to
John Larkin

of

gate

current

MHz,

any

response

config

coax

hard to

+

I think it was a 3090ES, around 1991ish.

Cheers

Phil Hobbs

--
Dr Philip C D Hobbs 
Principal Consultant 
ElectroOptical Innovations LLC 
Optics, Electro-optics, Photonics, Analog Electronics 

160 North State Road #203 
Briarcliff Manor NY 10510 

hobbs at electrooptical dot net 
http://electrooptical.net
Reply to
Phil Hobbs

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posted

This was a little more serious than bypassing FPGAs:

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It's the output stage of a 17 kilowatt MRI gradient coil driver. A 120 amp output pulse settles to PPM levels in 100 usec or so. On a thing like this, current sloshing around, drops in traces, transient thermoelectrics, and even eddy currents in heat sinks, matter.

There are times when power distribution dynamics needs a lot of attention. In most products, it doesn't.

some

looks

If the pours are electrically stiff, the stuff works.

add

What is engineering. Should I claim that 94.831% of our stuff works the first try? Over what time base?

What fraction of your designs work, can be shipped with minimal hacking, on the first try, the first PCB etch?

Do you do a full frequency-impedance analysis of every power plane on every board that you design, in the context of known dynamic chip power requirements? If you don't, you are following rules of habit, which is essentially superstition. I do that too, I just have simpler rules.

I don't add caps until it works. I put a few on the schamatic, place them on the PCB layout, and it works. It's not worth hours of engineering to either make it (somehow) work better, or to pull a few cents worth of caps off the BOM.

It's too easy a problem to spend much time on.

Well, we've recently done 4-lane and 8-lane PCI-Express-over-cable boxes, but that's only 2.5 GBPS per lane. No *full* design analysis, not many caps, all 330 nF and a couple of polymers, works fine.

--

John Larkin         Highland Technology, Inc 

jlarkin at highlandtechnology dot com 
http://www.highlandtechnology.com 

Precision electronic instrumentation 
Picosecond-resolution Digital Delay and Pulse generators 
Custom laser drivers and controllers 
Photonics and fiberoptic TTL data links 
VME thermocouple, LVDT, synchro   acquisition and simulation
Reply to
John Larkin

He's only talking about one CPU. There are as many as six in a 3090, plus two channel directors (essentially another 370 style CPU) and channels (perhaps 256 I/O ports).

Mainframes weren't so much computing machines as information switches. Databases were where the money was, not MIPS.

Reply to
krw

on

cables

of

that

Oh yeah. The bragging rights are in MIPS/MFLOPS but the money is in databases; think search engines yahoo, google, ask, etc.,

?-)

Reply to
josephkk

I used to maintain a Z80B video effects system that had a 1000 A, 5 VDC power supply to manipulate live NTSC video at a broadcast station. It filled an entire rack.

Reply to
Michael A. Terrell

On Tue, 15 Jan 2013 21:41:58 -0500 rickman wrote in Message id: :

There was a system built back in the mid 90s that utilized 9000 Pentium Pro CPU chips that was built for the Dept. of Energy. I was hoping I could find some more details on the power supply (although there may have been multiple power supplies) but there doesn't seem to be any thing out there other than total power consumption of 800KW. If it was a single power supply it must have been a monster.

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Funny that just 10 years later and you could have the same processing power with only 44 quad core Xeons.

Reply to
JW

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