MS-DOS 3.20 (07-07-1986) problem on early IBM PC 5150

ibmpc5150

I figured out that MS-DOS 3.20 (07-07-1986) doesn't boot on IBM PC 5150 correctly (BIOS rev.1 -- 04/24/1981 , BIOS rev.2 -- 10/19/1981) with 128KB or higher RAM

But IBM PC-DOS 3.20 (12-30-1985) has no problem on its machine
This problem is only with MS-DOS 3.20 (07-07-1986).

MS-DOS 3.21 (05-01-1987) seems to be fixed this problem.

Anyway, MS-DOS 3.20 (07-07-1986) is only version which doesn't work on IBM PC 5150 rev.1/rev.2

SomeGuy

Is this the vanilla Microsoft MS-DOS? Many OEM version do fall down on their faces trying to boot on IBM or other clones, even when they are supposed to be compatible.

Is the problem specific to the BIOS?

It is not too surprising they would have missed that, as most serious users probably upgraded to rev 3 in order to use expansion cards with ROM extensions.

ibmpc5150

SomeGuy wrote:

Is this the vanilla Microsoft MS-DOS? Many OEM version do fall down on their faces trying to boot on IBM or other clones, even when they are supposed to be compatible.

Is the problem specific to the BIOS?

It is not too surprising they would have missed that, as most serious users probably upgraded to rev 3 in order to use expansion cards with ROM extensions.

Of course it is Not suprising issue, but I report the fact.

This result is from Microsoft MS-DOS 3.20 Genuine.
If this were from OEM vendor or modified DOS, I wouldn't report this fact.

I think this is Microsoft's problem because this was solved from DOS 3.21.

buricco

You could try replacing io.sys with renamed ibmbio.com from PC DOS 3.20.

ibmpc5150

buricco wrote:

You could try replacing io.sys with renamed ibmbio.com from PC DOS 3.20.

http://www.pcjs.org/disks/pc/dos/microsoft/3.20/

This issue is reported on PCjs.