OK, a little back-ground on me, so maybe this makes a little more sense to follow. I have had 3 years of electronics schooling, a little over 2 years of Electrical engineering, and been a licensed electrician for around 4 years after a 5 year apprenticeship with specialties in digital control design and instrumentation.
This doesn't mean a hill of beans other than I have a small notion how digital electronic devices are controlled on some level. My logic is somewhat different than a programmer when looking at devices such as data drives much of the time. I've been posting my thoughts without really going into an explanation of any depth ... maybe this will clarify what _is_ going on in _my_ head. > > a zero-ohm resistor is for circuit protection and yes pin 30 is > > ground on regular IDE as is pin 2. > > What does "circuit protection" mean? Ok, let's assume something internal in the ADM shorts out in a bad place We will also assume you are using the ADM as designed to use software via a special IDE controller to specify when and what is write-protected. This resistor has _no_ effect on the circuit _other_ than limiting the amount of current and voltage running across it. It technically should overload and burn out this resistor and protect the precious motherboard you just paid all this money for. In reality, this is almost never the case, but it is accepted good engineering practice from my experience. > I said the writing of *commands* not data. The lack of commands > is what yields the lockup, from my understanding. I was not > claming that write protect is possible by blocking DIOW or DIOR. > Rather it's the exact opposite as you found. Yes, I understood that, but I didn't state that I felt WP is possible w/o defining a software filter of _any_ kind, which is what I'm interpreting you saying on an extremely low-level here. You are defining what the manufacturer is intending to do and sell at a much higher price than a plug-in adapter to a toggle switch. > > > > If pin 30 is grounded (as normally done) and you add R8, > > R8 then grounds out pin 1 (reset) and _then_ the drive is write > > protected. > > The schematic show R8 exists. That's CS and my question > at this point, "Does R8 exist on an LD017 controller?" Probably not, the drive wasn't shipped to write-protect .. especially with a non-compliant ATA controller. They probably save around a nickel by not putting it in at all. The only reason pin 30 is used at all is for software filtering as stated on the data sheet. I interpet the data sheet as saying a jumper between pins 1 & 2 can be used _or_ pin 30 for software controller depending on the high/low state. > > Apparently the BIOS updated itself after the first boot and decided > > to work for me. > > </story> > > What BIOS are you referring to, and how does it update itself? The motherboard BiOS. I can't really explain this. When you put a 20 Gig harddrive in a Cyrix 333, why does it hang for ~30 seconds before booting. Checking the drive tables for a known drive type , then uses the best guess if not known, I guess. I really don't know anything about how BIOS hd detection really works. > > > In a nutshell, jumpering pins 1 & 2 on a regular IDE setup from > > around 1996 will write-protect a regular IDE drive. I will try this > > with a harddrive as soon as I get around to Syslinux'ing one. > > I don't follow. Have you disconnect to wires to pins 1 and 2 on the > drive, left them floating, and tied pins 1 and 2 of the cable side > together? OK, you have two IDE connectors on the ribbon cable. Plug one into the drive. Now put a jumper, or wire in a switch, between wires 1 & 2 on the other drive plug. This simply grounds out pin 1 (reset) as the data sheet and the hardware tech alluded to. Is this going to work perfect on all drives/mb's/BIOS's ??? I don't know, it is now working on the one machine I tried with no problems. I can't say for anything else. > > Can anyone else try and verify this for me ??? > > I have a cable and an old IBM drive I can doink with. > I'll let you know. Thanks, I think this could be of use to a couple of people besides myself anyway. > Can I be a little lazy and ask you what the logic is that > your trying to accomplish? What does grounding the reset > line do? Something that will allow me to write-protect an IDE flash or CF drive in a 1U half-slot rack case. Write-protection will be pure hardware ideally. Maybe I'm just nuts, but it's lying there working as I wanted right now. I like to thank everyone for inspiring to make strange opinions and attempt weird tricks. -- ~Lynn Avants aka Guitarlynn guitarlynn at users.sourceforge.net http://leaf.sourceforge.net If linux isn't the answer, you've probably got the wrong question! _______________________________________________ Leaf-devel mailing list [EMAIL PROTECTED] https://lists.sourceforge.net/lists/listinfo/leaf-devel
