guitarlynn wrote:
>
> On Saturday 09 February 2002 04:01, Jeff Newmiller wrote:
> > The altered states to start to come into focus. :)
>
> hehe, kind of scary, eh?
It's not the fear but how you deal with it. Facing down
a half dozen genius physicists is good times. They have
a lot of wit, and everybody like spherical cows.
> > This is a cmos logic device.. not a power driver. It will not burn
> > out any resistor.
Hence my unanswered question to Charles about his analysis to float
the line or gnd it. Doesn't sound kosher to me. It's a cmos logic
device, the fundamental element of our whole binary world. It's on
or off. Vcc or Gnd. I would create the following switch:
Vcc
o
|
|
|
o
/
\ 1K
/
\
o
|
|
|
o-------------- WP# --------> to controller chip,
| named LD017_A0
|
o
/
/
/ switch
/
/
o
|
|
---
- GND
.
is what we're talking about. The WP# line on the LD017
is low asserted. If you gnd that pin, then the ADM is
write-protected. That's in the pdfs, too.
>From what I've read in the pdf's, the solution I came up with
above is also how a it would be controlled through an IDE cable.
The cable would use low or high cmos signal levels. If it's correct
for the cable-controlled method, then why not for our custom
built cheapo switch setup? I say high and low, not float and low.
Refer to
http://www.ssti.com/products/pdf/519-58SM-LM8-192-01.000-DS.pdf
Fig 2-1, the bottom of page 8. It mentions using high and low
and shows their vaporware configuration.
> You often see resistors inline to limit current
> > (say, for LEDs or transients from off-board inputs), but these are
> > NEVER zero ohm resistors.
>
> I will have to agree with that, a real small diode would be more
> standard there, I've never seen a "0 ohm" resistor?
>
> > A zero ohm resistor is a piece of wire. It is not a fuse. I would
> > recommend that you re-read Charles Steinkuehler's analysis for the
> > most likely function of this (most likely not installed) piece of
> > wire.
>
> Yep, I did and what you are saying makes sense. Why would you
> call a piece of wire (a jumper) a resistor? It seems that you would
> call it "J8" or something or something along those lines. In any case,
> what "R8" does, as Charles noted, takes the Wait# from the LD017_A0
> to pin 30 (ground) on the controller.
That last sentence makes me go hmmm. I'm not sure that you
realize what IDE means. May I quote Webopedia:
'IDE INTERFACE
Abbreviation of either Intelligent Drive
Electronics or Integrated Drive Electronics,
depending on who you ask. An IDE interface is an
interface for mass storage devices, in which the
controller is integrated into the disk or CD-ROM
drive.
Being an integrated device, it has the controller on
the drive, or on the ADM. The controller on the ADM is
a microcontroller, model LD017_A0. If you look at Fig 1.1
on the the SST web site pdf spec sheet, you'll see it:
http://www.ssti.com/products/pdf/519-58SM-LM8-192-01.000-DS.pdf
> Mike said the tech told him that:
> "They use a hardware solution shunting R8 to ground", which indicates
> to me that R8 was designed to be a component besides a piece of wire.
> A shunt is typically a resistor or an inductor coil. A piece of wire
> would work, but probably not what the design team had in mind.
> Now, what the design(ers) had in mind, I won't necessarily guess at.
>
> > It seems to me that tying reset low would prevent the interface
> > circuitry from working... that is, the device would be write
> > protected, but it would also be read protected, so if it lost power
> > you would have to physically be there to enable reboot. This would
> > _not_ be ideal.
>
> No, I proved that by simply trying it. Logically, you make sense, but
> maybe that is why noone has gotten a typical ATA device to work
> this way in the years that it has been attempted. I proved that setting
> pin 1 to ground does _not_ disable read capabilities of the drive or
> the ability to communicate the Low-level hardware (BIOS).
Ok, first of all, I tested your hypothesis about jumpering pins 1-2
of an ide cable's empty second connector, and the computer won't post.
This was on a working IDE hard drive that was sylinuxed and was booting
and running Oxygen perfectly.
Secondly, let's backtrack a bit to the creation of hypothesis.
I'll show that the foundation for your hypothesis is flawed.
I'll cut and paste a bit. I said and you replied:
Matt > > The schematic show R8 exists. That's CS and my question
Matt > > at this point, "Does R8 exist on an LD017 controller?"
GL > Probably not, the drive wasn't shipped to write-protect .. especially
GL > with a non-compliant ATA controller. They probably save around
GL > a nickel by not putting it in at all. The only reason pin 30 is used
GL > at all is for software filtering as stated on the data sheet.
GL >
GL > I interpet the data sheet as saying a jumper between pins 1 & 2 can
GL > be used _or_ pin 30 for software controller depending on the high/low
GL > state.
You say, "I interpet (sic) the data sheet as saying a jumper
between pins 1 & 2 can be used...."
Ok, please remember that. A bit further down you go on:
GL > OK, you have two IDE connectors on the ribbon cable. Plug one into
GL > the drive. Now put a jumper, or wire in a switch, between wires 1 & 2
GL > on the other drive plug. This simply grounds out pin 1 (reset) as the
GL > data sheet and the hardware tech alluded to.
Neither the hardware tech nor the data *ever* alluded to grounding
pins 1 and 2 of the ide cable. Rather they alluded to jumpering
pins 1 and 2 of the vaporware WP# jumper that only exists on the
http://www.ssti.com/products/pdf/519-58SM-LM8-192-01.000-DS.pdf
file in Fig 2-1 on the bottom of page 8. In *that* figure only
does it show that you can jumper pins 1-2 on the adm itself.
These pins are not connected to ide pins 1 and 2 at all, but
rather pin 2 goes to WP# pin 30 and 1 goes to ground.
Over and over I've read in every one of their sheets that if
you ground pin 30 on the LD017 ATA controller, then you enable
write protect. The answer is that R8 does not exist. I don't
even have to see and ADM at this point.
It's been a learning experience as always. And thanks for the
impetus to poke around with digital a bit more.
Matthew
> As one
> of my old high school math teachers kindly beat in my head,
>
> "Sometimes 'PIAGO' is the only way to tell for sure"!
> (PIAGO ---> Plug it IN and Grind it Out)
>
> I'll try it with some other boards and ATA devices as soon as I get
> around to Syslinux'ing any of them, if noone else feels the desire
> to taking a chance on destroying some 7+ year old hardware.
> I find much of it by trash cans or at a DAV store for under $10,
> so I can afford to destroy one or two if it will benefit us.
>
> ~Lynn Avants
> aka Guitarlynn
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