IBMDOS vs MSDOS problem.

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March 14th, 2006, 04:11 PM
Dexahol

IBMDOS vs MSDOS problem.

This is one of the oddest problems I've seen in awhile. Generally, I'm pretty competent with DOS, but this one has me perplexed. And sorry for this being a bit long-winded. I figured you'ld need all the facts.

We have a laser control system that has an older embedded x86 computer in it. It uses DOS 5.0 as an OS, but since it takes commands from a larger piece of equipment, we can't alter that. We decided to use an old flea-market 486 as a "test" unit. I have the original floppy with minimul DOS 5.0 files on it:

COMMAND.COM
IO.SYS
MSDOS.SYS
FDISK.EXE
FORMAT.COM
MODE.COM
AUTOEXEC.BAT

. . . and then all the laser specific software.

I can boot from that floppy just fine. When I try to do a FORMAT C: /S, I get a "Please insert a DOS diskette in A:" type prompt. This is odd because it booted from this disk. So, I just manually copied the COMMAND.COM, IO.SYS, AND MSDOS.SYS files over. On trying to boot from the C: drive I get:

Can't find IBMDOS or IBMBIO . . . yada, yada, yada.

After doing some MS knowledge base searches I came up with the fact that some older DOS versions used those instead of IO.SYS and MSDOS.SYS. (But 5.0 should use the latter.) Anyway, I typed:

copy msdos.sys ibmdos.com
copy io.sys ibmbio.com

Now the C: drive boots up and runs fine. If you're still with me, that leads to this question:

How can a floppy with MSDOS.SYS, and IO.SYS, format and copy system files that then require IBMDOS.COM and IBMBIO.COM to operate? And I did make sure the floppy didn't have any hidden files on it. All attributes were cleared before proceeeding. This is just the strangest thing I think I've seen in awhile.

Thanks for reading.

Dex

Edit: Some quick last points. Here's the link to the MS knowledge base that says that 5.0 requires MSDOS.SYS and IO.SYS. (Scroll down aways.)

http://support.microsoft.com/kb/q66530/

Also, I typed "ver" and "command" and both report MS DOS version 5.00.
March 14th, 2006, 04:59 PM
Platypus

IBM DOS calls the files IBMDOS & IBMBIO, presumably the 486 has an IBMDOS boot sector (is it an IBM?). Copying the files re-named is a novel solution, I think re-writing the boot record using FDISK /MBR from the boot floppy would have been the standard solution.
March 15th, 2006, 04:05 PM
Dexahol

Its an old DEC (Digital Equipment Corp) 486. But it does the same thing on a modern P3 using System Commander to make a dedicated DOS 5.0 partition.
On the DEC, I did start by doing an fdisk. I wiped out the old partition and created a new one. I then reformatted it.

I did notice one thing. The three main files, (command.com, io.sys, and msdos.sys), were all dated with the same date and time - xx.xx.91 5:00a. However, the format command is dated 1992. I wonder if this format command isn't the original 5.0 version. Although, it doesn't generate a "wrong version" error.

Its just weird. :confused:
March 21st, 2006, 08:13 PM
Robert M

The format slash s command which executed from the floppy after booting with the floppy checks for the existence of the proper system files on the "current drive" and if not there, will display the message.
April 2nd, 2006, 10:10 PM
Dexahol

Quote:

Originally Posted by Robert M

The format slash s command which executed from the floppy after booting with the floppy checks for the existence of the proper system files on the "current drive" and if not there, will display the message.

But thats the thing - the FORMAT /S command works just fine. It formats the C: drive, copies over command.com, io.sys, and msdos.sys. I then reboot from the "new" C: drive. Thats when I get that error. I put the A: disk back in and just rename the io.sys and msdos.sys files to the "ibm" name style, and it works.

That's what doesn't make sense. Its obviously the same command.com. How can it require one naming convention on one disk, and the other on the other? Weird. ;)
April 3rd, 2006, 02:26 AM
jerry4dos

Is COMMAND.COM from the IBMDOS file set? If so, I wouldn't be surprised if its been customized by IBM to look for those files on the drive COMMAND.COM is run from.

In later versions of Windows, it's become popular for the supplied "Recovery Disk" to be customized to check for something specific in the target machine to make sure the disk isn't being used to install that OS on another machine.

Jerry
April 4th, 2006, 12:44 PM
Robert M

Dexahol
You said that the format c: /s command did not succeed in your first post didn't you? Remember you said it prompted for the diskette and then you performed some other commands?

I guess the copy command and the ver command does not check for the presence of the proper (or matching) files like the format command.
April 4th, 2006, 07:37 PM
Dexahol

Quote:

Originally Posted by Robert M

Dexahol
You said that the format c: /s command did not succeed in your first post didn't you? Remember you said it prompted for the diskette and then you performed some other commands?

I guess the copy command and the ver command does not check for the presence of the proper (or matching) files like the format command.

Yes, thats correct. I actually forgot about that since getting this far in the thread. :o But it's still odd that the floppy would boot, but require different versions of files that it, itself, needed.

Today I got some original DOS 5.0 disks from someone at work. I'll see what impact those have, then report back. I appreciate all the help so far, though.

Dex