DOS war stories

In honor of the IBM PC turning 30, I thought I’d tell some stories about my experiences with the operating system introduced with it, PC DOS (aka MS-DOS).
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4 more questions about RAID

Longtime reader Jim ` asked me a few more worthwhile questions while I was procrastinating working on yesterday’s post about RAID. Let’s go to Q&A format. Read more

How to revive an old PC

Somewhere, stashed in a corner of the basement or a closet, pretty much anyone who works on computers or even has just owned computers for a long time has a stash of obsolete hardware, stashed for a just-in-case moment.

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Why I generally buy AMD

I was talking to a new coworker today and of course the topic of our first PCs came up. It was Cyrix-based. I didn’t mention my first PC (it seems I’m about four years older–it was an Am486SX2/66).

With only a couple of exceptions, I’ve always bought non-Intel PCs. Most of the Intel PCs I have bought have been used. One boss once went so far as to call me anti-corporate.

I’m not so much anti-corporate as I am pro-competition.

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Operating System Not Found, Missing Operating System, and friends

So the PC that stored my resume got kicked (as in the foot of a passer-by hitting it) and died, and the backup that I thought I had… Well, it wasn’t where I thought it was.

Time for some amateur home data recovery. Here’s how I brought it back.This machine ran Windows 2000. The first trick to try on any machine running any flavor of Windows is to boot from a DOS boot disk containing FDISK.EXE and issue the command FDISK /MBR. This replaces the master boot record. A corrupt MBR is the most common malady that causes these dreaded error messages, and this is the easiest fix for it.

That didn’t work for me.

The second trick is to use MBRWork. Have it back up the first sector, then have it delete the boot record. Then it gives you an option to recover partitions. Run that, then run the option that installs the standard MBR code. I can’t tell you how many times this tool has made me look like I can walk on water.

No dice this time either.

Next I tried grabbing the Windows 2000 CD and doing a recovery install. This has brought systems back to life for me too. Not this time. As happens all too often, it couldn’t find the Windows 2000, so it couldn’t repair it.

The drive seemed to work, yet it couldn’t boot or anything. I could have and probably should have put it in another PC to make sure it was readable. But I didn’t have a suitable donor handy. Had there been such a system, I would have put the drive in, checked to see if it was readable, and probably would have run CHKDSK against it.

Lacking a suitable donor, instead I located an unused hard drive and put it in the system. I booted off the drive just to make sure it wasn’t a hardware problem. It wasn’t–an old copy of Windows 98 booted and dutifully spent 20 minutes installing device drivers for the new motherboard hardware. So I powered down, installed both drives, and broke out a copy of Ghost.

Ghost, as I have said before, doesn’t exactly copy data–what it does is better described as reinterpreting the data. This allows you to use Ghost to lay down an image on dissimilar hard drives. It also makes Ghost a fabulous data recovery tool. Ghost complained that the NTFS log needed to be flushed. Well, that requires booting into Windows (and I think that’s all that’s necessary), but I couldn’t do that. It offered to try the copy anyway, so I chose that. So it cranked for about 15 minutes. I exited Ghost, powered down, and disconnected the bad drive. I powered back up, and it booted. Fabulous.

Now I can use Ghost to copy the now-good drive back over to the drive that was bad in the first place. I’ll do that, but sending out the resume takes much higher priority.

Ghost won\’t let me use my monster hard drive!

Here’s a familiar problem, I’m sure.

You need to back up your laptop, so you buy a monster (200+ GB) USB or Firewire hard drive. And then you can’t use it in Symantec/Norton Ghost, for one of two reasons:

1. You can’t format a FAT32 partition bigger than 32 gigabytes.
2. Ghost chokes when it tries to make a file larger than 4 gigabytes.These are limits of the operating system, not Ghost. But there are workarounds.

To format a FAT32 drive bigger than 32 gigs, you need a DOS boot disk. If you don’t have a Windows 95OSR2 or Windows 98 DOS boot disk handy, you might try bootdisk.com, or download the latest version of FreeDOS, which now supports FAT32.

You’ll have to use good old FDISK and FORMAT, which is clunkier than Windows XP’s computer management, but at least it’s possible.

Ghost can choke when the image file exceeds 4 gigabytes in size because FAT32 won’t let you make a file larger than that. It’s a limit of the FAT32 file system. The workaround there is to split up the image. Pass Ghost the -SPAN -SPLIT=4095 parameters when you launch it to get around that problem.

Slimming down the bird: A 2.6 kernel for PCs with 4-8 megs

In case you haven’t read about it elsewhere, a new branch of the Linux kernel called -tiny was quietly released last month. Its main intent is for embedded systems, but I can see all sorts of uses for it. The smaller the kernel, the faster it loads off a floppy, so it’d be great for boot disks. Likewise for diskless machines that boot off the network.
Some people claim that compiling the kernel with the -Os parameter, as this branch permits, causes faster operation than compilations with the normal -O2. The theory is that the system spends more time in user space than in kernel space, and therefore, the kernel will almost never be in system cache, and therefore, the smaller it is, the faster it will operate. I’m sure someone who knows some specifics of how CPUs and caches work could validate or refute this. Even Steve DeLassus, who has both an electrical engineering and a computer science degree from one of the best universities in the world for that kind of thing, admits that sometimes these specifics get over his head. So if Steve doesn’t always know, then how am I supposed to know?

But the argument sounds good on paper.

With this kernel slimmed down as much as possible (no networking), it can boot in 2 megs. With networking, it can boot in 2.5 megs. With a comfortable set of features, it runs in 4-8 megs, which a mainline kernel doesn’t always do anymore.

Obviously, this is a perfect companion for projects like asmutils and uClibc/Busybox/Tinylogin.

Windows 98 CD-ROM drive not working? Try this

Windows 98 CD-ROM drive not working? Try this

Occasionally, a PC’s CD or DVD-ROM drive will stop responding for no known good reason. Sometimes the problem is hardware–a CD-ROM drive, being a mechanical component, can fail–but as often as not, it seems, the problem is software rather than hardware. Here’s what to do with a Windows 95 or Windows 98 CD-ROM drive not working when the same drive works just fine in another OS.

If Windows has both 16- and 32-bit CD-ROM drivers, it can get confused and disable the drive to protect itself. The solution is to remove the 16-bit driver, then delete the obscure NoIDE registry key to re-enable the 32-bit driver.

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Fare thee well, goodnight, and goodbye to my friend, OS/2

The Register: IBM has finally brought the Great Rebellion [OS/2] to a close.
The Register was the only online obituary that mentioned eComStation, a third-party OS/2 derivative that everyone forgets about. Interestingly, the product literature never mentions OS/2 by name, only bragging about its technology licensed from IBM.

The Reg also talked about OS/2 version 3 being positioned as a gamer’s OS. Maybe that’s ironic, coming from the suits at IBM, and that wasn’t how I saw it–I switched from Windows 3.1 to OS/2 because, coming from an Amiga, I was used to being able to multitask freely without a lot of crashes. Windows 3.1 crashed pretty much every day if I tried to do that. OS/2 knocked that number down to about once a year, and usually those lockups happened when I was running Windows apps.

Even though I never really thought of it that way, OS/2 was great for games. Since it used virtual DOS machines, each environment had its own memory management, so you could fine-tune it and avoid shuffling around boot disks or struggling to master the DOS 6.0 boot menus. Pretty much no matter what you did, you got 600K or more of conventional memory to work with, and with some fine-tuning, you could bring that total much higher than you could usually attain with DOS. Since 600K was almost always adequate, most games just ran, no sweat.

The other thing I remember is the speed at which DOS games ran. Generally, running it under OS/2 gained you a speed grade. A game running under OS/2 on a DX2/50 felt like a DX2/66 running under DOS would feel. An OS/2 wizard could usually squeeze yet more performance out of the game with some tweaking.

I have fond memories of playing Railroad Tycoon, Civilization, and Tony LaRussa Baseball 2 on my Compaq 486 running OS/2 v3.

And there was another really nice thing about OS/2. When I bought a shiny new Pentium-75 motherboard and CPU and a new case, I pulled the hard drive out of the Compaq and dropped it into the Pentium. It just worked. All I had to do was load drivers for my new video card, since it used a different chipset than my 486.

And the cult of OS/2 won’t go away just yet. The talk over at os2voice.org has me almost ready to install OS/2 again.

Reviving a laptop

The drive in my work laptop gave a S.M.A.R.T. error over the weekend. I never have had much luck with Hitachi laptop drives. Micron sent a replacement drive–an IBM, thankfully–and, doubly thankfully, the Hitachi hung on until today. So I whipped out Bart’s magic network boot disk–to which I’d added the 3c556 module necessary to get this Micron Transport LT on the network–and ran my copy of Ghost from a network drive. (It won’t fit on that disk, no way, no how. Not with all the other stuff crammed onto it.)
Depending on how far gone the drive is, Ghost can cope with failing hard drives, because you can use the -FRO switch to make it work around bad clusters to the best of its ability. So I initiated Ghost with ghost -z9 -fro (the -z9 tells it to use maximum compression, since the network is the bottleneck here) and made a copy of my disk to a network drive. An hour and a half later (ugh–do I ever miss Token Ring) I had a backup. So I swapped in the IBM drive and repeated the process in reverse. An hour and a half up, an hour and a half down. The data compression wasn’t the bottleneck.

And in the end, I had a healthy laptop again. The IBM drive is quieter and seems faster. I noticed it wasn’t the nice new 5400 RPM model (it’s a 4200 rpm drive) but it’s not a slouch. And it definitely doesn’t clunk as much as the Hitachi always did. I love Hitachi’s video equipment, but their hard drives have always given me trouble. IBM’s laptop drives have always been fine for me. And I know IBM took a lot of black eyes over the GXP desktop series, but think about the things that are known to cause problems with IDE drives:

Rounded cables
PCI bus overclocked beyond 33 MHz
Heat
Cables longer than 18 inches (the length of the wire–not the cable itself)
Certain VIA chipsets in conjunction with Sound Blaster Live! sound cards

IBM 75GXP and 60GXP drives were typically bought by people seeking performance. People seeking performance often do at least one of the above, intentionally or unintentionally. During the 75GXP’s heyday, the hottest chipsets on the block were made by VIA (Intel was still embroiled in the whole Rambus fiasco), and the sound card everyone had to have was the SB Live. I suspect the GXPs were more sensitive to these factors than some other drives and they really weren’t as bad as their reputation.

While rounded cables are good for airflow, they’re bad for signal integrity. Rounded SCSI cables are common, especially in servers, and have been for years, but SCSI takes precautions with its signals–most notably, termination–that IDE doesn’t. That’s part of the reason why IDE is cheaper. So yes, though ribbon cables do look really retro, replacing them with fancy rounded cables isn’t a good idea unless you like replacing hard drives. Get Serial ATA adapters and run your drives serial if you don’t think retro is cool. I’ve been conspiring for the last couple of years to get something semi-modern into my vintage IBM AT case, so I happen to like retro.

But I digress. I hope when the merger between Hitachi’s and IBM’s storage divisions happens, we get the best aspects of both rather than the worst.