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Vintage Computers Any vintage computer systems, calculators, video games etc., but with an emphasis on 1980s and earlier equipment.

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Old 11th Feb 2021, 12:38 pm   #1
TALKINGWITHPYE
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Default 486 PC. Help please.

Hello all, I have an old 486 computer which doesn't read the a:drive. I got a replacement interface card from a forum member but still I get FAIL TO READ DRIVE A: Has anyone had similar problems? I am wondering if the cable between the interface card and the drive has developed a fault or possibly a problem with the power supply. The mouse on the 9 pin connector works ok. I tried the interface card in different ISA slots all with the same results.

Dave
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Old 11th Feb 2021, 1:02 pm   #2
JimmyDeath
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Default Re: 486 PC. Help please.

Hello Dave

I would guess that a faulty disk drive is more likely than the cable or even just dirty heads.

Has the CMOS battery gone flat or nearing end of life, i.e. have you checked that none of the bios settings have changed.

Does the drive light come on/ can you hear the motor running when you try to access it?

Regards

James
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Old 11th Feb 2021, 1:30 pm   #3
Dave Moll
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Default Re: 486 PC. Help please.

From the previous thread it was established that the drive worked OK in another computer, and replacing the controller with an identical one has also failed tosolve the problem, which means either that the replacement interface card has the same problem or (more likely) that the problem lies elsewhere.

As suggested, the most likely possibilities are now:
a) the cable - make sure that the IDC connectors at each end are firmly in place and that there is no damage to the ribbon cable itself.
b) the BIOS settings have become corrupted - go into the settings to check that they are correctly set for the type of drive (if I recall correctly, this is usually entered by pressing DEL during startup).
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Old 11th Feb 2021, 5:04 pm   #4
Orakle42
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Default Re: 486 PC. Help please.

Remember that to address BIOS settings on startup that a wired keyboard is required, a wireless device will not work until the Machine has booted up. [I hope I am not telling somebody how to suck eggs!]

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Old 11th Feb 2021, 7:26 pm   #5
kellys_eye
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Default Re: 486 PC. Help please.

Does the drive make any noise, movement or indication (lights)? If not I suggest the IDC cable may be 'reversed' as ISTR that some don't have the keying position on them.
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Old 11th Feb 2021, 7:30 pm   #6
SiriusHardware
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Default Re: 486 PC. Help please.

I think this machine (a 486!) will be well before wireless keyboards were common - probably has a 5-pin din plug on the end of the keyboard cable.

If the problem is in the Bios setting the most likely cause is that the floppy drive type (in the bios) has somehow got itself set to the 'other' type of floppy - I don't recall any mention of what sort of drive the system has but if it is 3.5" maybe the bios setting is currently for 5.25", or vice versa.

Kellys_Eye, I believe this system was formerly working as configured and then just stopped working without anything being physically altered as far as TWP knows.
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Old 12th Feb 2021, 3:21 am   #7
ortek_service
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Default Re: 486 PC. Help please.

Also be aware that PC's set the Drive's Select number (0 to 3) to 1.
And have a 'twist' at the end of the cable, to swap the relevant select lines over, so that the controller card see's it as Drive 0 ( A: ).

Adding a second drive - also set to '1', at the middle of the (untwisted part of the ) cable, then remains at drive '1' ( B: ).
Although with 5.25" ones, you may need to ensure that only the end ( A: ) drive, has the termination resistor-network plugged into its socket

Although If it's all original, and once worked-OK, then this shouldn't be a problem.

It may also be worth checking you've got +12V at the drive
- 5.25" ones need this for the Motor, whereas 3.5" usually only need the 5V supply.

I did see a recent thread about controller card-issues, and do recall those multi-I/O cards (should have a few myself, and maybe brief instructions). There are quite a few links for the LPT/COM ports address . IRQ / DMA, but not sure if there was a secondary address etc. option for the FDC part.
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