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Nigel GuyFlag for United Kingdom of Great Britain and Northern Ireland

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"Newer" Hard disk in an old machine

We have a drill machine that has an old type of pc buried in it. When it boots up the Bios now can't find the Hard disk. Luckily we took a copy of the HD a few years back. The problem is the Bios is so old that it has the old Type 1 - 46 HD or 47 for a user defined ( which the current HD is ). It's going to be very tricky to find an 83mb replacement hard disk and as only understand the basic's of this type of bios what is the maximum hard disk I'll be able to install in there and it still recognise it (trying to increase my buying scope for a 'new' HD ).

Thanks for Reading
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Scott C
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Wow.  That's the old XT style HD

You might be able to find one on eBay or at a swap meet or flea market.
Definitely a challenge.

A couple questions:

(a)  What is the exact make/model # of the current hard drive?    I assume it's an RLL drive, but there were some variations in the early PC's, so it'd be best to confirm that.

(b)  Have you ever replaced the CMOS battery in that unit?   It's possible that you've simply lose the custom values stored in CMOS that define your drive, and the drive is fine, but the system doesn't know the correct settings to access it.   Do you have the custom values documented somewhere?

(c)  How much space was actually being used on the hard drive?    And how did you save the copy of the drive you made "... a few years back" ??   Just curious how you plan to restore that copy to a "new" drive.   There ARE a few RLL drives available on e-bay -- but they are NOT inexpensive (wish I'd kept all the ones I tossed over the years !!).
I think you need to identify what type of PC is buried into this machine.

If it is an XT type of machine then something like what is described here might work.  These are basically plugin cards to your motherboard and use CF cards to act as hard disks.  Getting an old XT hard disk is NOT recommended (by myself) as anything that old is going to die anyway.

This probably isn't a project for the faint-hearted but might prolong the life of your drill machine by using more modern components.
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is there any auto detect for Hard Disk in bios ? select it and Enter,  it can get the information needed for type 47 mode (numbers of heads, cylinders, ... )
it must work well if you then set the HD disk type mode to auto in BIOS.

Some BIOSes implement manual autodetection of IDE devices using the "Type" setting. By pressing {Enter}, the BIOS will autodetect the device, set the type to "User", and set the other numbers and options for you. Most BIOSes however have a dedicated menu entry for autodetecting all IDE devices.
I would bet that this well pre-dates XP and ran DOS.  What sort of connector does the drive have on it?  It could be MFM or RLL (two separate ribbon cables) or an IDE/ATA drive with a single ribbon cable and a 4-wire power cable.

I would agree with garycase about the battery.  I don't recall if you would get a message that the drive wasn't found if you had the wrong type set.  I vaguely recall that you'd get a different message in that case.

If the drive is recognized at all, I have a utility you can use to read from the drive the # of cylinders, heads, and total sectors that were in place when it was formatted.  I wrote it to deal with lost CMOS settings where you weren't sure of what had been used on the drive.

How tough would it be to replace the computer?  I'm assuming that there is a special controller card on it for the drilling machine.  What sort of motherboard connector does it use?

Specs on the computer and drive would help a lot here.
"... I would bet that this well pre-dates XP and ran DOS ..." ==> Agree it almost certainly pre-dates XP.   May be running MSDOS, or possibly WFW.    Perhaps some chance it's Win '95 or '98 ... but almost certainly nothing newer than that.
Perhaps an approach would be to find one of the early XT / ISA bus controllers for IDE drives which had its own, on-board "booster" BIOS.  You could then use any small IDE drive up to the BIOS capacity of the host motherboard, making the primary partition smaller than that capacity and not using any cylinders beyond that capacity.

That should be simpler than trying to deal with old WD or Wespercorp full-length MFM / RLL controllers and ST-2xx drives.
Agree -- that's why I had asked for details on how the image was saved ... as I think using an IDE drive would be FAR easier to find a replacement.    We really need more technical details of this system to really suggest a fix with any specificity.
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Hello all, and many thanks for your replies ! Apologies for not getting back earlier but there is always someone else who has something with a higher priority....

Ok so the HD is a Conner CFS850A.  (IDE/ATA drive with a single ribbon cable and a 4-wire power cable.)

The Bios load screen: 1992 Oak technology VGA Bios V1.06 (Amibios) - The hard disk selection is the old 1 to 47 - 47 being user entry where you put the cylinders, heads and sectors (1651, 16, 63 for the Conner)

The 'PC' is on a 486/386 Industrial CPU card, that's plugged into an AP-SL08 Board with various other cards ( VGA, serial/parallel, + four other cards  ( I did think about replacing the whole unit with anther PC but those four other cards don't look that standard so will require more investigation)).

I agree about old HD's on eBay that are expensive and you just have no idea how long they will last. I'm guessing I can't partition a larger HD to a small area and type in the cylinders / heads / sections to match ?

It is just DOS running with the program autostarting - The backup is just the contents of the hard disk. Plan to install the same version of DOS and then just copy the files back across....

So it looks like only option in reality is to buy an old HD and hope it doesn't die ?
"... So it looks like only option in reality is to buy an old HD and hope it doesn't die ? " ==>  Yes, that would seem to be the best choice.   There are several sellers with the exact same disk model, which would be the easiest replacement, since you wouldn't have to change anything.
Do you have any newer IDE/PATA drives around you could test?  I would expect that one would work using whatever cyl/head/sect settings you use but only to the capacity determined by those settings.  This would allow you to use a much newer drive.

I may complicate matters, but there are PATA-SATA adapters that will allow you to use a new SATA drive on a PATA controller.  There may be issues in your case (speed, for one) but the adapters are very inexpensive and worth trying if you have a SATA drive around.
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Gary Case
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What is the hard disk plugged into?  The PC motherboard or an expansion card on the backplane.
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Drill machine engineer suggested this fix last week, only had the adapter come in today, works really well.