View Full Version : No boot on 486DX

January 12th, 2009, 08:26 AM
It was alive & now it's dead!

History: Freebie given to me.
No brand name on pc or mother board
Cmos battery was dead, replaced.
Got it booted up to Win 95 & operating, found pictures of previous owner & told him I would try to retrieve them for him.
Tried to install network card (NC100) to no availe. Couldn"t install drivers with A drive.
Learned person at work recommended just putting HD into computer with Win98 and cdrw. Sounded easy & worked after comfiguring HD as slave.
After resetting HD to master & reinstalling in 486dx it wouldn't boot to Win95.

Hardware in PC: 2 HD, configured & recognised on start up.
1.44mb floppy drive
5.25 floppy drive
CDR drive
Tape drive
Graphics card

Tried Win95 boot disk and got nowhere.
Screen says to hold ctrl key to boot from disk
Then insert disk & hit enter.
When thats done every thing just stops.
Setup accessed by del key
set date & time
set floppy A as 1.44mb
set floppy B as 1.2mb
set master & slave HD settings
Boot sequence is set at C:A , and have tried A:C, No difference
Have tried enable A at boot, no good
In setup have tried optimal settings to no availe.

Have removed tape, cd, 5.25 drives & modem to eliminate any conflicts.
Still no changes.

Believe maybe A drive has never worked as I didn't test it after I got the PC operating. That's why I couldn't load drivers for network card.
Tried another working floppy drive, no change.

Anyway I believe I'm beyond my nuts&bolts knowledge and am looking for help.

Did I lose some 0's & 1's when moving the HD from here to yon?
I'm thinking something in the setup is keeping from recognising the A drive, but don't know what.

Appreciate all the help I can get.

Thank You


January 12th, 2009, 08:55 AM
Can you post a picture of the mobo ?
By any chance, does the floppy light light up continously from when you power it on ?

What size is your HD ?
It sounds like the 486 mobo isn't recognizing either the size, or the BIOS translation.


January 12th, 2009, 11:06 AM
Also, carefully check for bent or broken pins on the HD connectors. Sometimes things get creamed during cable acrobatics.

January 12th, 2009, 11:14 AM
Try the HD in the Windows 98 PC again as slave. Does it still work there?

Bendt pins does happen. It happened to my DIN to PS/2 keyboard adapter and my system locked up when using it. Also make sure that the cable is plugged in the right way and that all connectors are 100% inserted. Old flat-cables doesn't have tabs to prevent it from being inserted wrong.

January 12th, 2009, 04:49 PM
Sorry my camera is at work & I won't be back till Fri. night.

Will try the HD back in the other pc but is is being recognized by 486.

Going to have to get away from it for a bit to clear my brain.


January 14th, 2009, 07:15 AM
Sketch of mobo attached, sorry no camera available.
At least shows major components.



January 14th, 2009, 07:28 AM
Do you know what translation mode the 486 is using to map the hard drive ?

dengelland said...Learned person at work recommended just putting HD into computer with Win98 and cdrw. Sounded easy & worked after comfiguring HD as slave.
After resetting HD to master & reinstalling in 486dx it wouldn't boot to Win95.

When you set the HD to master, you also changed the jumpers on the hard drive itself, correct ? Also, and you probably know this, but I'll mention it anyway, you can do the following:

You've two ide channels, each supporting uo to devices.
With two devices on one channel, they have to be set master & slave.
With two channels &two devices, I'd recommend putting the HD as master on the primary channel, and the cdrw as master on the secondary channel.

Some IDE drives used to be fussy if they were master only, or master with slave present. What's the model of your hard drive ?


January 14th, 2009, 10:32 AM
2 hard drives; both on HDD1,
Western digital, wd2250 Caviar set as master on channel 1
Seagate ST3630A, set as slave on channel 1.

Presently have disconnected cdr from HDD2, and other drives other than 1.44 floppy on FDC.

Exploring WD while in other pc it has Windows and windows1 on it, along with DOS, so figure the boot comes from there.


January 16th, 2009, 06:12 PM
Patscc; Here is a better pic of mobo.

After a couple days of thinking, I believe I have gotten something out of kilter in the setup.



January 16th, 2009, 07:02 PM
Was it working with that RAM configuration before?

January 16th, 2009, 07:22 PM
How is it partitioned ?
Also, I'm wondering if in your BIOS setup you have a setting for Mode Type, and if so, is it set to Auto, LBA, Large, or CHS ?


January 16th, 2009, 09:56 PM
I will have to get it back together now to check on these things.

Thank You


January 17th, 2009, 10:05 PM
To let you know I found everything on the Motherboard, it is no longer unknown.
It's a M918i, model no supposed to be under sticker on bios.
Also known as PcChips M918i, Amptron DX-9300
AMIBIOS string 41-c100-001437-00101111-101094-486PCIMB-U

found it at http://motherboards.mbarron.net/486pci/m918i.htm

Now armed with all the information, I can get thing really out of kilter.


January 17th, 2009, 11:17 PM
:O Oops, he said the P****ps word!

Check Druids suggestion I would say, that raised an eyebrow with me too.

January 17th, 2009, 11:38 PM
In answer to Druid, yes, at least it booted up, I don't know how well it ran as I didn't test it all out. I moved the hard drive to another computer with cdrw to get pictures off it then moved hd back. In the mean time I changed battery and now feel I have something out of kilter.


January 18th, 2009, 12:29 AM
Sorry, I didn't know that Pc***ps was a bad word, is Amptron DX-9300 better? or Houston Tech ?
As you may have guessed I'm rather new to pc's.
They call me "Old Man" at work, but after seeing this sight, I tell them I'm "Vintage"


January 19th, 2009, 12:13 AM
The name PC Chips makes most of us old skoolers shudder when it gets mentioned, as these were known to be at the 'cheap and nasty' end of the market; the only boards that gave me more trouble than PC Chips were ECS Elitegroup (sorry for swearing).

I would check that all of the simms and sockets chips are properly seated, as they can 'creep' with the heating up and cooling down. Opening the case and tinkering may have just broken a dodgy connection that was suffering from 'creep'.

Was the board getting past the POST, or were there any beeps to give a clue as to what may be the fault?

Just as an aside; there is a possibility that when you put it into the Win98 machine, it may have changed something on the boot sector that is stopping Win95 from booting. I am thinking about FAT16 versus FAT32 conflicts here, what file system is set up on the original drive?

This is just a brain dump; if I think of anything else I'll get back to you.

January 19th, 2009, 01:11 AM
if it boots at all, try to boot it with a floppy disk.

January 19th, 2009, 01:29 AM
I have been doing some studing tonight and came up with a thought, which is just that for now, maybe someone can tell me if it has merrit.

I read about the difference in Win operating systems and ran into a didi about Win 3.1 used fat 16 and Win 95 used fat 32 files. Is it possible that beings this pc seems to be a 94 model that it originally had Win 3.1 installed and the optimal settings in bios call for fat 16 but then Win 95 was later installed and requires fat 32 file system. After changing batteries i have been going back to optimal settings and I will have to look but I think is fatt 16.

I will check today, Am working 12hr. nights this week end and my days at home are for sleeping, I'm a supervisor at work so i get to play & think a lot when no one is watching at night. But 486dx is at home.



January 19th, 2009, 03:01 AM
It might be that a simple fdisk /mbr from a boot floppy which will set the drive to FAT16 might just solve this. If the drive has been set to FAT32 by Win98, then the PC can't resolve the partition information, so no boot.

Win95 was happy to run under FAT16; it was only when you got to Win98 OSR2 that FAT32 became the standard. DOS was only finally left out when WinME came out (the less said about WinME, the better).