AARDvarks in your code.

Sucking the brains out of DOS

/dev/null — Sat, 12 Jan 2008 09:38:38 GMT

I read Raymond Chen's blog from time to time, somewhat because he's a really conversational writer, and somewhat because he's got lots of interesting things to say about the history of Windows. I was amused by this post about MS-DOS...

Whidbey kicks serious ass...

Core/Dump: opinion, babes and bondage... — Fri, 18 Feb 2005 01:18:00 GMT

 Good articles about .NET 2.0 and VS.NET 2005 - ASP.NET Whidbey- Storing User Information with ASP.NET 2.0 Profiles- ASP.NET Whidbey-...

re: AARDvarks in your code.

Norman Diamond — Thu, 19 Aug 2004 01:00:00 GMT

Sorry for two in a row. This appeared while I was editing my previous posting.

8/18/2004 9:29 AM Larry Osterman replied to mschaef

> That's true only because Win95 booted with
> DOS 7.0 - once it came up, all the DOS code
> was thrown away (unless there were 3rd party

Some of the DOS code was not thrown away. The protected mode and real mode code interacted with each other, resulting in at least two bugs for which Microsoft provided downloadable fixes and at least one for which Microsoft didn't. In some cases 3rd party drivers interacted too but they were not at fault. The same bugs were manifest when the user tried devices whose drivers were all built into Windows 95.

re: AARDvarks in your code.

Norman Diamond — Thu, 19 Aug 2004 00:55:00 GMT

8/17/2004 5:26 PM Larry Osterman

> Norman, that's a truely silly question,
> IMHO.

Compare it to the silliness of this. A retrospective essay on the AARD code asserted that there were valid technical reasons for the AARD code. One of the asserted reasons is that a mixture of code from Microsoft and other vendors might have been equally disastrous as code from Microsoft actually was all by Microsoft's self.

I agree that the possibility was there, the effects would have been disastrous, and Microsoft's code was (and likely still is in Windows 2000) disastrous.

But I think I'm not going to believe that this was one of the reasons for the AARD code.

> Of course the OS was tested for disk
> corruption. Not every possible scenario was
> tested, and obviously a bug was missed.

In Windows 95 obviously several bugs were missed, because there were more than one downloadable patch for W95A for bugs causing IDE disk corruption (in fact I probably named the wrong one a few days ago). Why was there no downloadable patch for the bug causing SCSI disk corruption? Microsoft did not remain permanently ignorant about this bug.

In Windows 2000 maybe there were only one or two missed bugs, maybe. They are more subtle than the Windows 95 case.

> But the testing was done.

Indeed there are additional clues besides your statement, demonstrating that testing was done. One SCSI card vendor had performed testing before I got hit by it, but unfortunately the first four SCSI cards I experimented with were from vendors who didn't know about it. The fact became more widely known later, other SCSI card vendors tested, AND Microsoft almost surely tested. Why didn't Microsoft provide a downloadable patch?

(Actually I have seen clues about an answer to this too, your company knowingly and willfully cared not a fig for the amount of damage your company did to end users outside of the US. But if you have any more useful answers, please let's hear them.)

For Windows 2000 and PCMCIA IDE hard disks, observe that testing was done for Windows XP while Windows 2000 was still on the market. Why was a fix released for XP and not for 2000?

There is one case that might or might not be a Windows 2000 bug. If the user attaches a SCSI disk that had been fdisk'ed by Windows 95, and opens Windows 2000 disk manager, Windows 2000 accurately determines that one of the logical partitions is corrupt but fails to determine that second one is corrupt. But if the user tells Windows 2000 disk manager to delete the corrupt logical partition, it actually deletes both, without warning. It is understandable how this might have been missed in testing. I don't know if this testing was actually done or not. I almost want to ask if you know, but then you'll answer this instead of the much higher priority questions that I asked above. Please, the others are far more important.

re: AARDvarks in your code.

Larry Osterman — Wed, 18 Aug 2004 16:29:00 GMT

That's true only because Win95 booted with DOS 7.0 - once it came up, all the DOS code was thrown away (unless there were 3rd party drivers like the CD-ROM driver mentioned) present.

re: AARDvarks in your code.

mschaef — Wed, 18 Aug 2004 13:31:00 GMT

"Norman, there IS no underlying operating system when running Win2K and Win95. "

Windows 95 depends just as much on DOS as does WfWG3.11+Win32s, despite the fact that it packaged DOS 7.0 with Windows 4.0 in the same box. Even file system interrupts can get routed through to real mode DOS under the right circumstances (a real mode CD-ROM driver, for example, and I suppose a real mode DOS-based network stack too).

Windows 2000 is totally different, of course.

re: AARDvarks in your code.

Larry Osterman — Wed, 18 Aug 2004 00:26:00 GMT

Norman, that's a truely silly question, IMHO.

Of course the OS was tested for disk corruption. Not every possible scenario was tested, and obviously a bug was missed. But the testing was done.

re: AARDvarks in your code.

Norman Diamond — Wed, 18 Aug 2004 00:17:00 GMT

8/16/2004 7:53 AM Larry Osterman

> Neither Win95 or Win2000 mess with the
> internals of the underlying operating
> system.

8/17/2004 8:07 AM Larry Osterman

> Norman, there IS no underlying operating
> system when running Win2K and Win95.

Right. Now that this is out of the way, can you say why Windows 95 and Windows 2000 were not tested to prevent corruption of hard disks? Your base note explained how bad things could be if Windows 3.1 were combined with another vendor's DOS instead of yours. Things could have been exactly as bad as things actually were (and are) with your company's Windows 95 or Windows 2000 all by themselves. You KNOW how bad disk corruption is. One question is why weren't these tested, but a bigger question is why weren't patches released after customers got to do your testing for you?

re: AARDvarks in your code.

Larry Osterman — Tue, 17 Aug 2004 15:07:00 GMT

Norman, there IS no underlying operating system when running Win2K and Win95. They are complete solutions, from the disk drivers to the user interface.

Windows 3.1 was not a complete solution. It relied on the OS for file services and other stuff (memory management, etc).

re: AARDvarks in your code.

Norman Diamond — Tue, 17 Aug 2004 00:40:00 GMT

8/16/2004 7:53 AM Larry Osterman

> Neither Win95 or Win2000 mess with the
> internals of the underlying operating
> system.

Huh?

In the W95 case, maybe you mean that the protected mode part doesn't mess with the real mode part, but that is still wrong. Microsoft released patches for IDE disks for W95A because the protected mode part DOES mess with the real mode part. Microsoft didn't release patches for SCSI disks for any W95 version because, well, we'll get to that.

In the W2000 case, what can you possibly mean?

> In the Win95/Win2000 corruption, was it an
> end-user application that was corrupting the
> system,

No end-user application is involved at all. A fresh installation of W95 on any vendor's PC, attach a PCMCIA SCSI adapter made by any vendor, and attach a SCSI hard disk made by any vendor. If the PCMCIA SCSI adapter is made by anyone other than Adaptec then the vendor's SCSI driver has to be installed; Adaptec's driver was built into W95. The fdisk command is broken. The solution is to use the vendor's partitioner utility that the vendor intended for use under Windows 3.1. Too many vendors didn't know that W95's fdisk was broken so they told customers to use fdisk instead of the vendors' own utilities under W95.

With a fresh installation of W2000, it isn't even necessary to use a vendor's driver. Windows 2000's built-in IDE driver handles PCMCIA IDE adapters. But something in W2000 is badly broken during boot time. Interesting that for Windows XP Microsoft provided a downloadable patch containing the characters W2K in its name, but for Windows 2000 Microsoft did not provide one. But I didn't test the thing under Windows XP because fortunately I was able to return the device during its warranty period, which was before XP came out.

> or was it a hardware combination that wasn't
> tested?

No kidding. Microsoft built some drivers (and fdisk command) into its OSes, didn't test them, and produced disastrous results.

Here in your blog entry you point out the possible disastrous effects of mixing earlier Windows systems with other vendors' DOS clones, so I ask why Microsoft didn't test Microsoft's own OSes in order to avoid the exact same disastrous effects?