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Question about 48-bit LBA hard drive functionality

98 Guy

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Assuming that we're talking about a hard drive (IDE) larger than 137 (or 127.5) gb that's connected to a motherboard that has bios support for 48-bit LBA, then my questions are:

1) If the drive is formatted as a single partition (single volume) and given a read or write operation at (or just past) the sector that contains the boundary point (137 or 127.5 gb point) will that read or write "wrap" back to sector 0, and if it's a write operation will such a write dammage the MBR or the FAT tables?

2) If the drive is partitioned as 2 volumes, then does that matter? In other words, will a read or write at or past the 137/127.5 gb point result in the same situation regardless of how the drive has been formatted?

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I'm not sure if I understand the answer.

If I have a 160 gb hard drive, and if I format it as an 80 gb primary partion and an 80 gb secondary partition, such that I have an 80 gb C drive and an 80 gb D drive, then:

1) will I completely avoid the 137 gb boundary problem? Or

2) will a read/write past the 137 gb point of the drive (which would be at the 57 gb point into the D drive) cause this sector-wrapping problem and hence would end up causing dammage to the fat area of the C drive?

(Some people think that formatting a large drive into smaller volumes of each less than 137 gb is a way to avoid this problem. Are they right?)

Where is the author of the modified ESDI_506.PDR? He/She should know the answer.


If I remove or rename ESDI_506.PDR, windows uses "compatibility-mode" (which is DOS mode?) to access the (IDE) hard drives. If ESDI_506.PDR is removed or renamed, then does this 137 gb problem "go away" ?

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  • 2 weeks later...

Yep, partitions have nothing to do with the wrapping bug. Making several small ones will cause just as much damage as a single large one without the patch.

I've installed this fix, and while it does correct the wrapping issue, there are weird issues I've encountered with the Recycle Bin size limits, as well as IE's cache size limits not behaving correctly. Just so you know. A minor nuisance all in all though, and still much better than being stuck at 127 GB.

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The author was banned (shame) but you can read the long thread where just about the whole thing was described as to the whys and hows and how to apply the fix, etc.

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The author was banned (shame) ...

And why was the author banned?

Yes, I would say that is a shame, given that he/she was seemingly so talented and provided the win-98 community with very valuable resource (the updated ESDI_506 driver that is, and maybe more?)

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Don't know. But there was a post from a mod saying that she hadn't cooperated with some unspecified thing after several warnings. The mod also said that if we discuss it we can get banned too! I paraphrase, but that was the jist of his post.

Yes, LLXX was very giving to the community as far as offering assistance as well as designing several of the patches that are still being used in some of the update packs. Most of the gurus we have are awesome at creating guides, keeping track of updates, troubleshooting problems, packaging installers, etc, but she was a rare one that actually wrote code that fixed up serious issues.

Had a funky sense of humor too. I enjoyed the sarcasm. Obviously someone else did not. I know I've been dissed on forums a lot more strongly and childishly than anything I've ever read from her and the perpetrators have always gotten off scott free.

Who knows? Maybe she laid it on too rough on a mod who can't take a joke. Extreme loss to these forums. I have no idea what happened but I tend to be sympathetic to the accused as my diplomacy kind of stinks. I got fired from more jobs because of true things I've said even though my work was excellent. Most folks can't handle the truth. Shame on them. They'll make the money now but be burning later.

Repressed anger guy signing off for now.

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  • 5 weeks later...
There is a long thread about all that. Please read it.

are you referring to this one ?


there are some posts in that thread about using a external ATA card but no clear results.

What about using a 48bit LBA compatible IDE controller card instead of the onboard ATA IDE channels ? has anyone ever tried using such a card to see if Win98 can work with physical hard drives bigger than 137gb ? (say, a hard disk of 160gb with one 127gb partition + another partition with the remaining space ?)

I have a 160 gb hard drive and my bios recognizes it right and so does Win98 but as soon as I step over the 127gb the data get corrupted and my system freezes for a while. Fortunately I didn't lose the < 127 GB content but I was wondering if using a external card would help me have the remaining space of the drive.

here's what Seagate says on their website :


Windows 98 - Operating System - 127 GB - 137 GB Limitation

At this time Windows 98 does not natively support 137GB drives. However, there are some 3rd party utilities that will allow you to see the full capacity of the drive once the operating system has been installed (no support for installing to a full size partition).

Below you will find solutions for overcoming this capacity limitation with the advantages and disadvantages for each method.

3rd Party Controller Cards

Using a 3rd party controller card will allow you to overcome the 137GB limit by providing 48-bit support at the BIOS level and by providing drivers with 48-bit support. This is arguably the safest method for utilizing your drives full capacity:


* Card provides 48-bit support at the BIOS level

* Card comes with 48-bit support drivers

* Card is plug-and-play compatible


* Card must be purchased

* An additional PCI slot is required

Software Driver Updates (800 Series Intel Chipsets Only)

The Intel Application Accelerator (IAA) adds 48-bit LBA support for the 800 series Intel chipsets. Intel also provides information on how to identify your chipset.

WARNING: If your system's old boot drive is less than 137GB and uses a drive overlay program (DDO) to overcome a previous BIOS capacity limitation (such as Disk Manager or DiscWizard and identifiable as a blue banner box before the operating system loads), then the Intel Application Accelerator is incompatible with your system. If you have this legacy configuration, the Ultra ATA host adapter card is the only solution for Windows 98SE. If you install the Intel Application Accelerator on this type of system, loss of data will occur. If you are not sure if your system uses a DDO, contact us.


* Will provide support for the full capacity of drives larger than 137 GB

* No charge


* May be incompatible with some versions of drive overlays that could cause the system not to boot.

Software Driver Updates (Non-Intel Chipsets)

At this time, there are no software driver updates available.

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I don't think somebody answered my question concerning the Intel Application Accelerator on that topic, so I ask here again - I have a i850E chipset and the 2.3 Application Accelerator installed. Does this (referring the quoter of the post above) mean, that I am in fact able to use bigger harddrives than 127gb just like 2000 and XP can?

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Holy cow! But I'm not gonna test it for the sake of it to find out that it doesn't work in the end. So I think I'll need a definite confirmation, maybe someone here has a setup with IAA and can tell me about it.

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From what I've read, if the IAA is compatible with your system then it can be used (obviously). If you can use it, then it is substituted as the driver used just like what happens when using a Via board with the Via Sata/Raid driver and a Sata hard drive. So, since that ESDI pdr driver is not doing anything you can run your big hard drives as long as your bios supports 48 LBA. Just don't use Scan Disk and Defrag. You'll need 3rd party tools instead. And set msconfig not to run Scan Disk on a bad shutdown.

And yes, if you use a PCI IDE Controller card then you install its own driver that also is used instead of the ESDI pdr driver. So then you can also use the large hard drives as long as your bios supports the 48 bit LBA.

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Don't use scandisk and defrag? What the...so it's basically completely senseless or I have to get an other prog to scan and defrag...that's bad. But as I would be only storing files on it, I would not have to scan or defrag too soon anyway.

Edited by xtrm
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Well, Windows 9x/Me ScanDisk can be used if you never select the Thorough Scan option. The normal files/folders scan is okay. Disk Defragmenter is a definite no-no. Neither of these will see the sectors past that big hard drive limit as being healthy and will do damaging things to them if it encounters them.

Any new commercial defragmenting program will not have any problems. Norton Utilities 2002 was the last stand alone version and has full 9x/Me compatibility in Norton Disk Doctor and Norton Speed Disk to be perfect substitutes for the built in Windows versions (which are by the way, Norton Disk Doctor and Norton Speed Disk without the Norton GUI and the additional features). It's just that the versions that come with Windows 9x/Me don't have that 48bit LBA compatibility.

So if you can get your hands on that you could do your full thorough disk scans and defrags. Just do a custom installation and uncheck the Norton Unhide feature so you don't get that stupid Norton Recycle Bin that interferes with some stuff. You could also install it anyway and go into its options and delete all the files it protected and then turn it off and rename the Recycle Bin back to Recycle Bin, but it's better not to install it and have it mess with things in the first place. And you'll also want to make sure System Doctor is not set to run at Windows Startup.

The only things you need are Disk Doctor and Speed Disk. Win Doctor is nice but it does do some funky things in its fixes to programs that install in a way that uses an inserted cd to run, or use files not activated in the registry until used (like some games and Microsoft Office, as well as DotNET stuff). Better off with no registry cleaner or a more modern one. So you install the whole thing except Norton Unhide Wizard but only use those 2 programs.

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