Commodore 486sx-25 - boot from hard drive

[Kulgan]

Hehe, forgot to attach pics. Do it all the time :/

You're probably right that what I am thinking is not the battery. I have nothing against throwing together a few parts when I know where to stick the end result. But without that... well.. yeh...

I would write the .img files with dd on another old comp I have, but I have a teacher who should have the installation disks around - which I can always duplicate if i need to.

I have set the date to past 2000 before, but that's not really the problem. It's the hard drive settings. They are erased every time the mobo runs out of power, and it then resorts to the defaults - at least, that's my theory, based on booting and checking the setting many, many times.

Google gives mentions of the same machine, without actually presenting any useful information (Closest matches are "Commodore C486SX-20" and "Commodore C486-25C" on http://support.microsoft.com/kb/83210/en-us ).

Also:

DT 486SX-25 80486SX @ 25 MHz, SVGA, 4MB RAM, 80 MB HD.
* DT 486SX-25 80486SX @ 25 MHz, SVGA, 4MB RAM, 120 MB HD.

- http://www.zimmers.net/commie/docs/cbm-products.txt (about half way down)

So this thing was produced. I don't have some sort of imaginary box sitting here. But it can't have been very popular.
List of Commodore machines:
http://www.xs4all.nl/~lagendr/Menu/COMP.htm

What I have is close to this one:
http://www.xs4all.nl/~lagendr/Pagina/COMP-PC486-25.htm

However, my "Intel Inside" sticker is red, not blue (O.o), and the on/off swith is to the right of the floppy drive. (The two on the left are reset and turbo - whatever turbo does.)

I'm trying to find better documentation for it, but I don't think Wikipedia so much as mentions it, so I don't think I have much chance on the rest of the web either.

[mips]

Those silver rectangular things with the ? are what provides the PC with it's clocking signals as in how fast the cpu or bus operates at.

You might want to check for a battery somewhere inside the actual case, I have seen batteries that are seperate from the motherboard before.

[Bungo Pony]

JonUK76, I recall the soundblasters with the IDE connector on them. In fact, I think I have one around here somewhere. As far as I know, it was just a regular IDE controller. Older PCs had their IDE controllers on ISA cards instead of on the motherboard which it looks like is the case with this computer.

I don't see anything that resembles a battery on the motherboard either, unless it's beside the RAM (which I cannot see from the pics). And it definately could be a battery mounted in the case (usually with velcro) that connects to the motherboard, but I don't see a connector anywhere for it.

Those items that you circled are crystals.

I also seem to recall seeing the silver 3v battery on some ISA cards in the past, but don't quote me on that one as my memory is a bit foggy on that issue.

(The two on the left are reset and turbo - whatever turbo does.)

From what I recall, the turbo button cuts down your CPU speed which I believe was to help with compatibility for older software that ran too fast on 'modern' equipment. Most PCs back then had turbo buttons.

That's probably the last PC that Commodore manufactured before they went TU. Definately an interesting PC!

I have set the date to past 2000 before, but that's not really the problem. It's the hard drive settings. They are erased every time the mobo runs out of power, and it then resorts to the defaults - at least, that's my theory, based on booting and checking the setting many, many times.

I'd forgotten about that. I don't blame you for wanting to get that problem fixed, but unfortunately I can't see anything in your pics indicating the location of the battery, or a connector for the battery. If I knew the pinout, you could probably solder a battery directly to the processor, but you REALLY need to be careful that you solder the right pins!

[Kulgan]

Ok, so I knew this would happen. I was poking around in the area around the RAM, looking for something even vaguely resembling a battery, when I see BATTERY on the board. Couldn't have been more obvious.

It is indeed an external battery, in a little plastic box, tucked under the bar that holds the PSU in place. I'm not sure I want to open it, so I havent. It weighs less than a standard AA battery, and the label says it's 3.6V.

The connectors aren't soldered on - they have their own little connectors. This makes things one hell of a lot easier

Battery reads:

3.6V High energy lithium battery warning:
Fire, Explosion And Severe Burn Hazard.
Do Not Recharge, Disassemble, Heat Above 100C
Incinerate Or Expose Contents To Water

(no, ucwords was not done by me... ) and the same in German. Yay.

As I said, I'm hesitant to open the plastic encasing, even if it looks like there's one section of it that's "meant" to come off.

Edit:
Took it apart. Wasn't as interesting as I could have hoped. Looks like an old camera battery. Gives between 0.07 and 0.08V - looks like it was (part of) the problem?
I guess the next step is finding something to replace it with. Would it be OK to just use two AAs? 0.06V shouldn't make a difference anyway, so long as it's 0.06 less... I think?

[Bungo Pony]

Excellent!

It looks like it's basically the same battery that I pointed out on that other circuit board.

You'll probably want to solder three AA batteries together (1.5 v each). The extra .9 volts shouldn't hurt anything, but the lack of the .6 volts might cause problems as your batteries lose charge over time.

When connecting the batteries, connect plus to minus, just like you were putting them into a ghetto blaster, but use wire to connect them together.

Before soldering each end of the battery, take a knife or sand paper and scratch each end to make it a bit rough. The solder will stick much better. After, put the batteries into a case (or wrap them in electrical tape) preferably away from the motherboard, just in case they end up leaking from leaving them in for a long period of time. Use the connector on the old battery to connect the new ones. Connect the red wire to the + end of your battery 'circuit', and the black wire to the - end. Double check the voltage with a meter; it should be a bit higher than 4.5v. Connect, and away you go!

[Kulgan]

Awesome. Thanks!

So it should be a series rather than parallel circuit, then. Time to see if I can actually find the soldering iron. Haven't used it ages

update:
Got it working, though it's probably the messiest job ever done. The batteries weren't quite 1.5V, so it gives out pretty much exactly 3.7
Testing...

It's working. At least, it booted twice in a row without having to enter in the settings again, and it's still 2008. Very good indeed.

Thanks for all the help! I'm just waiting for the DOS disks before I can install. Now I've got that warm fuzzy feeling you get when you fix something broken
Just hope DOS installs OK, and I'll see what I can do with those drivers mentioned earlier. Thanks all!

[Bungo Pony]

Great stuff! Hope your install goes well and getting all the drivers you need working. That's probably the most difficult part.

[Wobedraggled]

Commodore made filing cabinets too, I would kill for one of those.

Cool stuff.