Booting (or not) a 386

In message , Graeme writes

Ignore that. Repeated CTL-ALT-DEL seems to have fixed the signal problem, BUT error message tells me the internal battery (Real time Clock) is discharged. It seems that the BIOS defaults to boot from drive A (the floppy), but I can change that to C, but, because the battery is flat, the change is lost when rebooting, and it again tries to boot from A. No, I can't find the original boot disc, although it must be here somewhere.

In the meantime, if I leave the PC on, will the internal battery charge, or is it not rechargeable? PC has probably not been booted for 20 years.

Its probably beyond its life so try sticking a new battery in. AIr Elonex were easy ones to get into and play with.

In message , Mark Allread writes

Oh good; thank you. I had visions of something soldered to the board.

Have now found a boot disk, but that does not help because, with battery flat, BIOS has no record of either hard or floppy drives. I can set, but the settings are lost on reboot. Bugger.

Not like the machines that had the CMOS battery *built into* the RTC chip ...

You had to unsolder the chip (without blowing it), solder in a socket, replace the dud chip to allow the PC to boot, then - with PC live - swap dud chip for new one, load up the debugger, and issue an OUT to the new chip to start the clock running.

BTDTGTTS.

Some are, some aren't. But are usually easy to get to and find out by the part number.

There's a chance that may be the case but I don't recall Elonex being that stupid.

If the battery is easily swapped then that is the first step. BIOS can follow.

They were mostly non-rechargable button cells but I did have one that had a rechargeable battery. Not usually too difficult to replace, just take a look inside at the motherboard and it should be pretty obvious.

The motherboard battery is certainly not rechargeable in any computer I've ever had. Just get a new cell for it.

On a good day you might get enough leakage to the backup battery allow you to reboot without having to re-enter the CMOS details. I had a partable go that way and on the second failed reboot it would start.

If you actually want to use it swapping the 2032 cell or whatever it happens to be for a fresh one will get you another decade.

In something 20 years old it could well be a 3.6V Nicad / rechargeable that would be soldered onto the Mobo.

If it is such and you didn't want to remove the board to replace it, you could snip the leads off and just connect a 'remote' (rechargeable) battery to the remaining legs.

However, assuming it is a rechargeable and isn't NFG, it *might* recover enough to hold the CMOS values, at least over a reboot. ;-)

Cheers, T i m

You can buy a new battery cheap. I did.

Can't think of any on desktop mothboards, but certainly some laptops have rechargable CMOS batteries.

Some designs had the battery integral to the RTC chip.

Just last week I decommissioned an Elonex PC 425x. If your 386 has been manufactured in a similar way then there will be a fairly bulky box which has been plugged into a DiL socket on the main board. This contains the BIOS chip and RTC battery potted in resin.

There's no way to replace the battery in this package but other people have had success from piggy-backing a two-AA battery pack across the relevant pins.

For what its worth, I didn't attempt to do any of this but I reclaimed all the data by taking out the hard drive, changing the jumper-pins on it from "Master" to "Slave" and plugging it into another computer with IDE drives and configuring it as drive "D". Then I copied all the stuff across from one to the other. The other computer being marginally more modern with USB ports and the like, I then transferred everything to a memory stick. (It didn't have to be a very big memory stick!)

Hope this helps Nick

Dallas DS12887 as I recall.

Re-reading that, I realise I could have copied directly from drive "D" to the memory stick. Doh!

Nick

It is on this Acorn RPC which is actually slightly newer. All my PCs have non rechargeable, though. But don't have one that old.

That's the badger !

When we needed one (1991, so pre internet) there was no retail outlet in the UK. My brother had to go to Birmingham to the sales office where they gave him one (they hadn't the admin to sell one. Ten thousand, yes. One, no :) ).

As I said, replacement was hairy - you needed the PC up & running to be able to send the pulse to start the new chip clock.

I used them on the PS/2 Model 55 - it was obviously better designed! Plug it in and it worked.