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Seeking help on reviving an IBM 286 clone

J

John

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Joined
Mar 17, 2004
Messages
32
I was lucky enough to find a 286 in working order, missing the hard drive only. I used a 486 machine to make a boot disk with some of the basic DOS files on it. What happens is it runs all the way up to where the A:> should show put never gets there. Any advice on what I've done wrong. Thanks in advance! :?

PS.. The boot disk I made will boot the 486 machine.
 
The first thing that comes to mind for me is memory. Either there isn't enough or you have some bad RAM in the area where DOS wants to load.

The other option is a bad disk drive that isnt' reading the DOS files correctly.

I'm not sure how your machine is configured but if you can swap the floppy drives or banks of RAM then you can hopefully isolate the problem if it's either of those.

Another possiblility that you may not be able to fix or test for is that the BIOS just isn't compatible. A call to a BIOS routine that isn't there or that isn't returning what DOS wants can lock up the machine.

Erik
 
Thanks for the reply Eric! How would I tell if the RAM is no good? When the computer is booting it goes through the memory check with out any problems. Screen shows "Starting MS-Dos" and "Himem is testing extended memory..." and then says "OK" the cursor drops down one line and just blinks. This is where the A:> part is supposed to appear. Any additional comments would be helpful.

PS.. I not a tech - I'm a draftmans longing for the computers of my school days.
 
Hi John;

I am not a MS/DOS expert or anything, but I have sure played around with many versions over the years, and have made tons of different config.sys and autoexec.bat files, I have written up.

Maybe you can use the 486 to open up your config.sys, and edit it, and try and removing the 'DEVICE=C:\DOS\HIMEM.SYS' or its equivalent on your config.sys.

Then try and boot the 286 without memory management, to see if the computer will at least boot up correctly.

Try and keep the config.sys and autoexc.bat files as simple as possible, with just the basics, (and hopefully boots up the computer fine), and then add from there.

Obviously though, you are going to want to use anything past 1 meg of RAM, you will need to run a memory manager.


A good bit of stuff I found:
"286's can use expanded and extended memory but can't handle UMB's (upper memory blocks). You can load DOS high but you can't load any device drivers or TSRs into UMBs (upper memory). To configure extended memory you can load HIMEM.SYS and load DOS high by setting DOS=HIGH but you will have to get a special third party expanded memory manager to configure expanded memory (EMS). The memory manager should come with the expanded memory hardware. The EMM might conflict with HIMEM.SYS, so the HIMEM.SYS might have to be replaced with one that is compatible"

Hope some of this info was helpful.

Chris
 
Vic user makes a good point. Clean out the autoexec.bat and config.sys files (or rename them completely) to see if the offending items are in there.

If the RAM tests properly on boot then it's probably good although the post check isn't as exhaustive as a full RAM test or actual use.

Good luck!

Erik
 
Thanks guys! My autoexec.bat file is already as simple as it can get only containing one line "@echo off", however the config.sys file has a few more lines:

DEVICE=A:\HIMEM.SYS
DOS=HIGH,UMB
DEVICE=A:\EMM386.EXE NOEMS
FILES=30
BUFFERS=20

I'll rewrite it to read:

FILES=30
BUFFERS=20

and see how that goes.
This computer has 2 disk drives A: (3 1/2 " 1.44mb) and B: (5 1/2 " 1.2mb). I would swap these and boot from the 5 1/2 " drive except that My 486 machines 5 1/2 " drive won't format a system disk for some reason (virus problems I think;)). My main concern is that I will be able to run DOS 6.2 on this older machine. I do have DOS Ver3.3 if all else fails. Please keep up the suggestions. I'm sure we can get this old computer up and running!
Thanks again!
 
John wrote:

DEVICE=A:\HIMEM.SYS
DOS=HIGH,UMB
DEVICE=A:\EMM386.EXE NOEMS
FILES=30
BUFFERS=20
-----

Hi John;

I would just get rid of the "DEVICE=A:\EMM386.EXE NOEMS" statement.

Everything else looks fine.

Chris
 
Great! Still boots the 486 system. I can't wait to get home and try it on the 286 system. I'll be sure to post how it turns out. Make sure to check back tomorrow to find out how this all turns out :!:
 
Oh, and I think you should get rid of ",UMB"

Just pop in:

DOS=high

Since you want DOS loading into high memory, but you do not want DOS to handle the upper memory area.

I have never run DOS 6+ on a 286 before. I have only gone as high as 5.0

Good luck again

Chris
 
Booting a 286

Booting a 286

I think I'd boot first with no autoexec.bat or config.sys. That should work if it's a fully compatible computer. Remember that in the early days there were some not so compatible dos computers that had to have special versions of dos.

I think most of the PCs were pretty compatible by the time the 286 came along so that's probably not an issue but it's a possibility.

If it won't boot successfully without a config.sys and autoexec.bat that means it's either got a hardware or compatibility problem.

I remember running into an old XT machine when I only had dos 3.2 and it wouldn't work on it. I got it to work on a copy of dos 2.11 but a lot of things weren't right. I can't recall the brand name now but someone found the special dos for it and it was fine.

You can find websites with bootdisks to download for practically any computer. You get them as an IMZ file and they have pointers to the program that converts that to a disk. Of course you need a computer with a 5.25 floppy to use that. There is a dos version of it.

I don't have a link for one of those websites but I've seen them fairly recently while looking for something else so I know they're still around. A bit of googling should find them.

Barry
 
You mean I don't need to have an autoexec or a config.sys file on a boot disk in order to get the computer to load up? Just have my DOS disk in the drive and go? Let me know, I'm interested.
Thanks
 
John said:
You mean I don't need to have an autoexec or a config.sys file on a boot disk in order to get the computer to load up? Just have my DOS disk in the drive and go? Let me know, I'm interested.
Thanks
Click to expand...

Correct. Both files are optional.

That used to be my first course of action with DOS problems. Just rename those two files to something else and boot "clean."

Erik
 
Success, the disk works (and so does the computer). It looks like the older unit can not run the emm386 program. I also removed the umb reference from the second line. All I need now is a hard drive. Strange though, the hard drive wire leading off the HDD card only has a 32 pin conector. Anyone with any insite please post a reason why. Thanks to all of you for your help with this.
 
I'll try to post a picture of it tomarrow (Saturday) night. It won't knock your socks off but... it will make it clearer what we're talking about. Only the HDD/FDD board has pins the other end of the cables have a slot connector. I pulled a hard drive out of a 486 machine but couldn't use it because it has pins on the back of the HD.
 
John said:
Strange though, the hard drive wire leading off the HDD card only has a 32 pin conector.
Click to expand...

Are you sure it's not 34 pins? (That would make it MFM or RLL or ESDI or...)

32 pins would just be strange.
 
John said:
Success, the disk works (and so does the computer). It looks like the older unit can not run the emm386 program. I also removed the umb reference from the second line. All I need now is a hard drive. Strange though, the hard drive wire leading off the HDD card only has a 32 pin conector. Anyone with any insite please post a reason why. Thanks to all of you for your help with this.
Click to expand...

When you say 32-pin connector, do you mean it's actually a 34-pin connector with a coupla pins missing or cut off? Also, check to see if there is a second, 20-pin connector present. While this still won't tell us the exact type of drive, (MFM, RLL, ESDI) it'll help narrow it down. If you can find a name/model # on the controller board mebbe someone can look it up for ya.

--T
 
Your right Terry! It is a 34 pin and it does have a second connection, most likely a 20 pin. I pulled an old seagate HD out of another computer that I had laying around and I'm trying to get it to work. The only problem is I can't remember how (which direction) the cable attached to the HDD board. I guess I have a 50/50 chance on getting it right.
 
John said:
I guess I have a 50/50 chance on getting it right.
Click to expand...

Look on the board for a tiny 1 (or 34, or both) next to the header, the stripe on the ribbon cable goes on the pin 1 end. On the drive end, there's a key cut in the circuit board, that's nearest the pin 1 (stripe) end. AND, be sure the drive itself is set to the first position if it's to be the C: drive.
 
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