"BIOS problem" solved

J. P. Gilliver (John) wrote
Rod Speed wrote

I've never had a problem with my samsungs.

Sounds painful!

Nope, completely painless.

Any of the small molecular weight alcohols are fine.

The SATA cable should not be bent until it kinks.

That's true of any signal cable like that.

This has an impact on the dielectric insulation inside
the cable. And can change the cable impedance.

Cable impedance just isnt a problem with digital signals.

If it wasn't, you wouldn't be worrying about kinks above.

I don't worry about kinks above.

It's an analogue world

Nope.

- especially at the sort of frequencies we work at these days.

Not in the sense that the cable impedance matters.

But even back in the days of 10 megabit ethernet, impedance was
relevant (75 ohm coax, IIRR). That's why, ideally, you had terminators.

But PATA didn't and SATA doesn't either.

Paul wrote
J. P. Gilliver (John) wrote
Rod Speed wrote

The SATA cable should not be bent until it kinks.

That's true of any signal cable like that.

This has an impact on the dielectric insulation inside the cable. And
can change the cable impedance.

Cable impedance just isnt a problem with digital signals.

If it wasn't, you wouldn't be worrying about kinks above. It's an
analogue world - especially at the sort of frequencies we work at these
days. But even back in the days of 10 megabit ethernet, impedance was
relevant (75 ohm coax, IIRR). That's why, ideally, you had terminators.

OK, here's a couple waveforms. The smooth one is what the unbent cable
will look like. The one with ringback, would be when the cable is kinked.

Not with SATA.

Try as I might, including the word "SATA" in my Googling, does not dig up
actual SATA waveforms for me to post.

Because cable kinking isnt a problem with SATA.

So I have to make do with whatever waveforms I can find.

http://ts4.mm.bing.net/th?id=HN.6080...5&pid=15.1&P=0
http://www.micron.com/-/media/images...d_data_eye.png

Those arent relevant to SATA.

That's the kind of measurements I'd want to see, if bending
the cable and studying what kind of a difference it makes.

It clearly doesn't if you can't turn them up with google.

The smooth waveform in those examples, shows the pulse template
on the screen at the same time as the waveform. The dark blue diamond
in the center, checks eye closure. The top and bottom blue rectangles
check for overshoot. The waveform is automatically normalized to fit
in the scope window (so you don't have to adjust the gain and offset
knobs on the scope). The pulse template is met by TX and RX designers,
and is an "agreement" as to what their end has to do, in order to work.
So you check your design (disk drive or motherboard), to see if it is
making the right quality of waveform.

No point with SATA.

If the waveform touches the template, it doesn't mean "instant death". But
if two marginal pieces of equipment get connected together, the room is
hot, the +5V voltage feeding the equipment is low, there might be
transmission errors.

Not with SATA.

Passing the template means you have some margin against conditions like
that.

And that is what SATA ensures.

I would want to see the kinked cable tested, to see how much
waveform distortion results from kinking one of the two conductors.

That isnt going to happen with a SATA cable.

Kinking both of them the same amount, while it degrades the waveform,
might not be as effective as kinking just one conductor.

And is what happens with a SATA cable.

The SATA cable is a miniature dual twinax (one pair for serial TX, one
pair for RX). And when I say "kink", I'm referring to the
compression of the shield around one of the two conductors in
that pair.

That isnt going to happen with a SATA cable.

The twinax conductors are differentially terminated
at the receiver, in 100 ohms or so.

(SATA cable cross-section)
http://www.satacables.com/assets/images/IMG_188353.jpg

Rod Speed wrote:


That isnt going to happen with a SATA cable.

Thanks for providing the incentive for me to keep searching.

http://h20566.www2.hp.com/portal/sit...4892.199480143

"Never bend a SATA data cable tighter than a 30 mm (1.18 in) radius.
Never crease a SATA data cable."

Notice that SATA power cables are not mentioned. This is because SATA
power cables are not coaxial or twinaxial in nature, and there is
no AC impedance to worry about in that respect. A SATA Power cable should
not be bent so tightly as to break the copper wire inside.

Paul

Paul wrote
Rod Speed wrote
Paul wrote

The SATA cable is a miniature dual twinax (one pair for serial TX, one
pair for RX). And when I say "kink", I'm referring to the compression of
the shield around one of the two conductors in that pair.

That isnt going to happen with a SATA cable.

Thanks for providing the incentive for me to keep searching.

http://h20566.www2.hp.com/portal/sit...4892.199480143

"Never bend a SATA data cable tighter than a 30 mm (1.18 in) radius.
Never crease a SATA data cable."

That isnt for the reason you were talking about.

Notice that SATA power cables are not mentioned. This is because SATA
power cables are not coaxial or twinaxial in nature, and there is no AC
impedance to worry about in that respect. A SATA Power cable should not be
bent so tightly as to break the copper wire inside.

On Thu, 06 Nov 2014 05:34:42 -0500, Paul wrote:

Rod Speed wrote:


That isnt going to happen with a SATA cable.

Thanks for providing the incentive for me to keep searching.

http://h20566.www2.hp.com/portal/sit...4892.199480143

"Never bend a SATA data cable tighter than a 30 mm (1.18 in) radius.
Never crease a SATA data cable."

Notice that SATA power cables are not mentioned. This is because SATA
power cables are not coaxial or twinaxial in nature, and there is
no AC impedance to worry about in that respect. A SATA Power cable should
not be bent so tightly as to break the copper wire inside.

Paul

Apropos of nothing (although I offer thanks for being motivated to look
further above!), I still remember as a child not understanding how
electricity could still get to the light bulb when there was a knot in
the wire.

Although some here might think otherwise, by "child" I mean when I was a
kid of 4 years of age, not when I was 19 years old.

--
Gene E. Bloch (Stumbling Bloch)

Gene E. Bloch wrote:
On Thu, 06 Nov 2014 05:34:42 -0500, Paul wrote:

Rod Speed wrote:

That isnt going to happen with a SATA cable.
Thanks for providing the incentive for me to keep searching.

http://h20566.www2.hp.com/portal/sit...4892.199480143

"Never bend a SATA data cable tighter than a 30 mm (1.18 in) radius.
Never crease a SATA data cable."

Notice that SATA power cables are not mentioned. This is because SATA
power cables are not coaxial or twinaxial in nature, and there is
no AC impedance to worry about in that respect. A SATA Power cable should
not be bent so tightly as to break the copper wire inside.

Paul

Apropos of nothing (although I offer thanks for being motivated to look
further above!), I still remember as a child not understanding how
electricity could still get to the light bulb when there was a knot in
the wire.

Although some here might think otherwise, by "child" I mean when I was a
kid of 4 years of age, not when I was 19 years old.


Transmission line cables are a little different, in that
abusing the dielectric, changes the characteristics of
the cable when passing GHz signals.

Transmitter ---- R0 ---- Coax -------+---- Receiver
(z0) |
R0
|
Ground

What that diagram is meant to convey, is both the transmitter
end and the receiver end, should match the AC impedance (Z0)
of the cable. If you do that successfully, no signal
bounces off the end at the receiver and goes back towards
the transmitter. The signal then has "perfect integrity"
and has the same shape (potentially with high frequency loss)
as the source. If the cable has extremely long length,
you use line build-out, things like pre-emphasis, to
make a good looking signal.

http://en.wikipedia.org/wiki/Pre-emphasis

The SATA standard uses short cables, and no fancy signal processing.
So rather than repair any high frequency loss issues, they limit
the length of the cable. To allow the ESATA cable to be
slightly longer, they increase the launch budget (still
with no correction for high frequency loss).

SAS supports much longer transmission, and has some line buildout
capability. Which allows the thing to adjust to whether a
long or a short cable is in usage. Some config bits, allow
the SAS interface to change the emphasis settings.

On SATA, the seven pin interface would look like this.
And R3 (differential) is meant to match the R1 and R2 thing
at the other end. The receiver has enough sensitivity,
to compensate for the line loss. SATA supports full duplex,
and packets can be moving in both directions between
disk drive and motherboard, at the same time.

(drain wire)
TX+ --- R1 --- Twinaxial -----------+--- RX+
TX- --- R2 --- Conductors -------+ |
| R3
| |
+---+--- RX-

(drain wire)

RX+ ---+-------- Twinaxial ------- R1 --- TX+
| +---- Conductors ------- R2 --- TX-
R3 |
| | (drain wire)
RX- ---+---+

Compare that to the "peeled" diagram for the cable.
The center drain pin, goes to two physical drain wires,
in the construction of the cable. Construction would
have been marginally easier, with an eight pin connector.
I'm sure somewhere, the person who had to solve that
issue, must be cursing the SATAIO people.

http://www.satacables.com/assets/images/IMG_188353.jpg

That wiring diagram is just meant to give a transmission
line view of the interconnect. There are other circuit
details not include - AC coupling, 8B10B coding...

HTH,
Paul

On Thu, 06 Nov 2014 16:23:14 -0500, Paul wrote:

Gene E. Bloch wrote:
On Thu, 06 Nov 2014 05:34:42 -0500, Paul wrote:

Rod Speed wrote:

That isnt going to happen with a SATA cable.
Thanks for providing the incentive for me to keep searching.

http://h20566.www2.hp.com/portal/sit...4892.199480143

"Never bend a SATA data cable tighter than a 30 mm (1.18 in) radius.
Never crease a SATA data cable."

Notice that SATA power cables are not mentioned. This is because SATA
power cables are not coaxial or twinaxial in nature, and there is
no AC impedance to worry about in that respect. A SATA Power cable should
not be bent so tightly as to break the copper wire inside.

Paul

Apropos of nothing (although I offer thanks for being motivated to look
further above!), I still remember as a child not understanding how
electricity could still get to the light bulb when there was a knot in
the wire.

Although some here might think otherwise, by "child" I mean when I was a
kid of 4 years of age, not when I was 19 years old.


Transmission line cables are a little different, in that
abusing the dielectric, changes the characteristics of
the cable when passing GHz signals.

Transmitter ---- R0 ---- Coax -------+---- Receiver
(z0) |
R0
|
Ground

What that diagram is meant to convey, is both the transmitter
end and the receiver end, should match the AC impedance (Z0)
of the cable. If you do that successfully, no signal
bounces off the end at the receiver and goes back towards
the transmitter. The signal then has "perfect integrity"
and has the same shape (potentially with high frequency loss)
as the source. If the cable has extremely long length,
you use line build-out, things like pre-emphasis, to
make a good looking signal.

http://en.wikipedia.org/wiki/Pre-emphasis

The SATA standard uses short cables, and no fancy signal processing.
So rather than repair any high frequency loss issues, they limit
the length of the cable. To allow the ESATA cable to be
slightly longer, they increase the launch budget (still
with no correction for high frequency loss).

SAS supports much longer transmission, and has some line buildout
capability. Which allows the thing to adjust to whether a
long or a short cable is in usage. Some config bits, allow
the SAS interface to change the emphasis settings.

On SATA, the seven pin interface would look like this.
And R3 (differential) is meant to match the R1 and R2 thing
at the other end. The receiver has enough sensitivity,
to compensate for the line loss. SATA supports full duplex,
and packets can be moving in both directions between
disk drive and motherboard, at the same time.

(drain wire)
TX+ --- R1 --- Twinaxial -----------+--- RX+
TX- --- R2 --- Conductors -------+ |
| R3
| |
+---+--- RX-

(drain wire)

RX+ ---+-------- Twinaxial ------- R1 --- TX+
| +---- Conductors ------- R2 --- TX-
R3 |
| | (drain wire)
RX- ---+---+

Compare that to the "peeled" diagram for the cable.
The center drain pin, goes to two physical drain wires,
in the construction of the cable. Construction would
have been marginally easier, with an eight pin connector.
I'm sure somewhere, the person who had to solve that
issue, must be cursing the SATAIO people.

http://www.satacables.com/assets/images/IMG_188353.jpg

That wiring diagram is just meant to give a transmission
line view of the interconnect. There are other circuit
details not include - AC coupling, 8B10B coding...

HTH,
Paul

What does all that have to do with my youthful "understanding" of wire?

--
Gene E. Bloch (Stumbling Bloch)

Gene E. Bloch wrote:


What does all that have to do with my youthful "understanding" of wire?

Well, my young friend, this is wire with blue
chewing gum inside. Try a bite...

http://www.satacables.com/assets/images/IMG_188353.jpg

Pauk

"Gene E. Bloch" schreef in bericht
...
On Thu, 06 Nov 2014 05:34:42 -0500, Paul wrote:

Rod Speed wrote:


That isnt going to happen with a SATA cable.

Thanks for providing the incentive for me to keep searching.

http://h20566.www2.hp.com/portal/sit...4892.199480143

"Never bend a SATA data cable tighter than a 30 mm (1.18 in) radius.
Never crease a SATA data cable."

Notice that SATA power cables are not mentioned. This is because SATA
power cables are not coaxial or twinaxial in nature, and there is
no AC impedance to worry about in that respect. A SATA Power cable should
not be bent so tightly as to break the copper wire inside.

Paul

Apropos of nothing (although I offer thanks for being motivated to look
further above!), I still remember as a child not understanding how
electricity could still get to the light bulb when there was a knot in
the wire.

Although some here might think otherwise, by "child" I mean when I was a
kid of 4 years of age, not when I was 19 years old.

--


I always thought that uploading to a friend in Switserland took more time
than the other way round because it had to go up the mountains!



--


|\ /|
| \/ |@rk
\../
\/os

On 06/11/2014 19:04, Rod Speed wrote:
Paul wrote
Rod Speed wrote
Paul wrote

The SATA cable is a miniature dual twinax (one pair for serial TX,
one pair for RX). And when I say "kink", I'm referring to the
compression of the shield around one of the two conductors in that
pair.

That isnt going to happen with a SATA cable.

Thanks for providing the incentive for me to keep searching.

http://h20566.www2.hp.com/portal/sit...4892.199480143


"Never bend a SATA data cable tighter than a 30 mm (1.18 in) radius.
Never crease a SATA data cable."

That isnt for the reason you were talking about.

PLEASE EXPLAIN.


Notice that SATA power cables are not mentioned. This is because SATA
power cables are not coaxial or twinaxial in nature, and there is no
AC impedance to worry about in that respect. A SATA Power cable should
not be bent so tightly as to break the copper wire inside.



--

Brian Gregory (in the UK).
To email me please remove all the letter vee from my email address.