Recovering from dead CMOS battery

beer enigma

OK, I have on old machine on which the CMOS battery has died....its an ancient Digital PC5100, but works nicely on my network & I'm kinda attached to it !!

Problem is, powered up with a new battery & its doesn't recognise the hard drive, floppy or the monitor for that fact...black screen...I'd say the BIOS has totally lost its settings - if it doesn't see the floppy, how am I gonna recover this ??

DonkeyStyle \o/

Losing the harddrive settings is to be expected... if you have a much older system, you might not have the luxury of IDE auto-detect and will most likely have to take the harddrive out and read the label to discover its heads/cylinders/sectors/etc... which you can then enter in the CMOS setup easily enough.

I'd say getting the floppy back would entail little more than switching it to the proper drive type... it might be set on something daft by default.

The black screen sounds like your biggest problem right now... but I'd think it unlikely that the new CMOS battery completely screwed your display.
Unless you've got both onboard VGA and a PCI/AGP card, and the BIOS has defaulted to one or the other since the loss of its CMOS settings.
If that's not the case, then I'd say it's likely that you just upset the display card while changing the CMOS battery... try re-seating it a few times, they can be quite fickle like that, I've had cards/mobos that refused to display if the card was even slightly out of its sweet spot.

I'd have thought the BIOS would fall back to its on-chip defaults in the absence of a working CMOS... defaults that I assume are flashed into the eeprom along with the rest of the bios... how a default BIOS setting could prevent your display working is leaving me with a noodle-scratcher.

Another possibility is whether it's expecting an AGP or PCI display card by default... so it might be worth trying one of both just incase... though I was under the impression that this BIOS toggle was just to set which card was to be primary in a dual/multi display card setup... worth a try though.

I'd think it a bit of a freak occurance that the bios would be completely fried just by changing the battery, but as always, I'm open to correction :v:

PS. Is the battery the right way up?!

SouperComputer

if its a REALLY old machine, it may not be able to auto-detect the drives. You will manually have to enter the LBA, sectors etc as printed on the drive in BIOS.

I havent had to do that is over three years though!

DonkeyStyle \o/

Is there an echo in here? :v:

beer enigma

Lads, Lads....if it were just a case of manually entering the drive details, I'd be in happy valley by now.....

No, this baby has lost all of its settings. Video is integrated into the motherboard, so no disturbing video card etc.

This literally looks as though when the battery went, the bios lost its brain ! - we're talking a 1997 P133 here btw.

Just checking the Digital site today & I have a nasty feeling that the bios is totally dependent on the CMOS battery & therefore the poor old pc is defunct....

Any old guys on here like me remember the P133's & have a bios trick up their sleeve

DonkeyStyle \o/

Well I'm not "old", but I've had my share of old machines... started out with a 386 in '97.
I've been through a lot of PCs and I can't say I've ever heard of a ROM BIOS slitting its wrists because the CMOS battery was replaced. :eek:
Certainly never happened to me. (touch wood)
The very nature of ROM chips is that they can keep their data without needing to be powered... all the CMOS battery would be doing is keeping your configuration options... which the BIOS itself should have defaults for anyway.
I'm not saying it's impossible by any means, but there are other avenues of troubleshooting you could follow.
You could instead work on the more optimistic assumption that the BIOS is simply using its programmed defaults... and if it is, then what changed bios settings could cause the behaviour you're experiencing?

What signs of life are there? Whirring fans? LEDs? Montior coming out of sleep? ... when you say "black screen", is the screen black because it's it hasn't come on, or black because it's recieving a blank screen from the PC? (assuming of course that you're not using some poxy pre-DPMS dinosaur monitor)
It could be any number of other things that were disturbed in the process, ram, cpu, cables, other pci/isa cards... it might be worth giving everything a good going over... a system-strip as they say.

Though if it is, as you suspect, a corrupt BIOS, then that's game over... unless your mobo has a dual bios, which I've only seen with more recent motherboards... you can apparently re-flash them physically from the outside if you have the right equipment, or pry out the chip and replace it with a working one, but I've never known anyone who went to the trouble of doing this.
If it were me, I'd just give up the ghost and replace the whole motherboard.

SouperComputer

Tis a funny one alright. Generally the BIOS is a flash and then CMOS keeps the settings for BIOS if there is a charge, IE from the battery.

Have you gone through the usual rigmarole of disconnecting all connectors, including power (Either ATX or AT ) and hooking one up at a time.

Also, leave the CMOS battery in, but give the CMOS jumper a short for 10 Secs with the power dissconnected.

Capt'n Midnight

http://h18000.www1.hp.com/legacysupport/digital/digitalpc_5100_specs.html

http://h18000.www1.hp.com/legacysupport/digital/pdf/31-51ref.pdf manual battery on page 83 no clues there, though the chipset is Intel 430TX PCIset (Triton TX)

http://www.scopeboy.com/usbmod.html mother board pic.

Some of the machines then were OEM'd by Olivetti IIRC

Try it without the battery ?

beer enigma

Thanks guys...Capt'n as ever some useful stuff there...

I think its a lost cause here.....fan is whirring merrily, disk spins up, but no beeps, no sound from the floppy, although if you put a disk in it, you get the green light, so there's power there.

Monitor has power as the light is flashing on the front, but thats it....same signal as if you just had the power lead in - its certainly not getting any signals from the pc.

I'll try everything thats been suggested & report back after the weekend, baut failing that....its gonna one one heck of a funeral cortege for this baby.....my poor poor 5100.....sob

DonkeyStyle \o/

Hey, old mobos like that are a dime-a-dozen these days... assuming it's a standard form factor and not some oddball design.