Never heard of that before-ever.

Some larger hdds could have their capacity cut down/limited for use in older systems. by using a jumper.

Rikintosh wrote on 2021-09-08, 05:31:

In the past, hard drives had settings printed on their labels that allowed you to "turn" a 3GB hard drive into a 10GB hard drive at the cost of lower performance.

Why was this possible? When should this be used? Why is it not like that anymore? How does it physically work?

Oh yeah, the days of downloading more hard drive space from the internet, amirite?

Funny how that actually became a thing with cloud storage...

Rikintosh wrote on 2021-09-08, 05:31:

In the past, hard drives had settings printed on their labels that allowed you to "turn" a 3GB hard drive into a 10GB hard drive at the cost of lower performance.

No, they didn't.

The only thing close to that are MFM drives formatted with an RLL controller. So a 40MB drive could become 60MB AND faster at the cost of reliability, but I don't think this is what you had in mind mentioning GBs.

Rikintosh wrote on 2021-09-08, 05:31:

In the past, hard drives had settings printed on their labels that allowed you to "turn" a 3GB hard drive into a 10GB hard drive at the cost of lower performance.

How about a photograph of that label?

While disk compression software do increase capacity 70-100%, I've never seen one that could triple the capacity. Such claims were made by software companies, not HDD manufacturers.

It's the other way around. You could limit larger drives to stay under a certain limit to work around BIOS, controller or OS limits. Eg. 40GB drives with jumper to do max 32GB (BIOS 65,536 cylinder limit) or 10GB drives that could be limited to 8GB to stay under the Int13h BIOS limit.

Wow, did none of you ever know that? Take any hard drive smaller than 20GB, especially if it's a Quantum, and read the small print above the jumper table. You access the bios, detect the hd, then go to the place where you set the date and time, which is why in the HD session it is possible to manually program C/H/S for so many years, even after the era of MFM units

I used this a lot for many years, with several hds, to accommodate content downloaded via p2p.

Take this 3.2GB hard drive for example, it can be a 12.7GB hard drive

That will be a 12.7GB drive and manufacturer provided a table for old BIOSes to allow for manual configuration of lower capacity.

The 8.4-Gigabytes BarrierNewer BIOS’s allow users to configure disk drives to go beyond the 528 MB barrier by using several BIOS translation schemes. However, while using these translations the BIOS using Int 13 functions are limited to 24 bits of addressing which results in another barrier at the 8.4 GB capacity.To overcome this barrier a new set of Int 13 extensions are being implemented by most BIOS manufacturers. The new Int 13 extension allows for four words of addressing space (64 bits) resulting in 9.4 Terrabytes of accessible space.Whenever possible the Quantum Fireball Plus AS 10.2/20.5/30.0/40.0/60.0 GB AT drive should be used on systems with BIOS that support Int 13 extensions. If that is not possible the following are some techniques that can be used to overcome this barrier:• Use a third party software that supplements the BIOS and adds Int 13 extension support.• Obtain a BIOS upgrade from the system board manufacturer. Many system board manufacturers allow their BIOS to be upgraded in the field using special download utilities. Information on BIOS upgrades can be obtained on the System Board Customer Service respective web sites on the Internet.• Insert the Alternate Capacity (AC) jumper on the drive (see Section 3.3.5).

Not really.
They have 1 housing for several different discs.
The smallest model has 1 platter inside, the biggest uses 4 platters. Just divide the 12.7 GB by 4 and you have the 3.2 GB.

However, when you have the 4 platter model it's up to you to enter a smaller size in your BIOS.

AlexZ wrote on 2021-09-08, 16:41:

That will be a 12.7GB drive and manufacturer provided a table for old BIOSes to allow for manual configuration of lower capacity.

Nope,its 3.2gb. Put it on any motherboard, even a modern one, it will be detected as a 3.2gb hd. If it was a 10GB hard drive, it would have CHS settings for up to 30GB.

When I bought it at the time, it was sold as a 3.2gb hard drive.

It will never be detected by a bios as being a bigger hd, even in an unlimited bios. Trying to configure it as a bigger hard drive results in loss of performance in exchange for greater capacity.

Rikintosh wrote on 2021-09-08, 16:45:

Nope,its 3.2gb. Put it on any motherboard, even a modern one, it will be detected as a 3.2gb hd. If it was a 10GB hard drive, it would have CHS settings for up to 30GB.

You can't get blood out of a turnip. Where do you think that extra "capacity" is coming from?

keenmaster486 wrote on 2021-09-08, 16:48:

Rikintosh wrote on 2021-09-08, 16:45:

Nope,its 3.2gb. Put it on any motherboard, even a modern one, it will be detected as a 3.2gb hd. If it was a 10GB hard drive, it would have CHS settings for up to 30GB.

You can't get blood out of a turnip. Where do you think that extra "capacity" is coming from?

And why the hell would the manufacturer waste money by offering a large capacity hard drive that is only and only detected as a hard drive with 1/6 full capacity?

Rikintosh wrote on 2021-09-08, 16:45:

Nope,its 3.2gb. Put it on any motherboard, even a modern one, it will be detected as a 3.2gb hd. If it was a 10GB hard drive, it would have CHS settings for up to 30GB.

It's 12.7GB for sure if it works with that setting and that capacity can be filled up. Perhaps some have failed to pass internal tests and were configured to report smaller capacity as if having only one platter.

here are some more hds with this type of table. Sizes don't make sense as "bios limitations"

I believe you are mistaken. It's only they had a single label, and a single manual, for the whole series of hard-drives and capacities, and offered the C/H/S settings on the label for convenience.
No offense but what you say makes no sense from both marketing and technical point of views. Even if it was technically possible, and I believe it isn't, it would be critically damaging in terms of public image of the brand's reliability if they said "hey it's a 3GB but you can set it to 12 but beware for your data, no guarantees" and the drives actually failed. And if the drives were actually able to do the bigger size, size=money, and they wouldn't sell them at the minimum size.

Here's the jumper manual for the TM series and the same table as your last picture:

You can download the full manual from there and you will see it's not specific to a particular model, but generic to the TM series:

https://www.seagate.com/files/staticfiles/max … _tm_jumpers.pdf

That is a 3.8 GB hard drive. If a modern motherboard "detects" it at a lower capacity, it's because it doesn't know what to do with it and is getting the lowest common denominator or something.

AlexZ wrote on 2021-09-08, 16:52:

Rikintosh wrote on 2021-09-08, 16:45:

Nope,its 3.2gb. Put it on any motherboard, even a modern one, it will be detected as a 3.2gb hd. If it was a 10GB hard drive, it would have CHS settings for up to 30GB.

It's 12.7GB for sure if it works with that setting and that capacity can be filled up. Perhaps some have failed to pass internal tests and were configured to report smaller capacity as if having only one platter.

Yeah it's risky. They would have planned their sizing to make the most of the predicted defect rates. However, then market forces come into play and they find they're "losing market share" because somebody else is selling 2.5GB drives at a psychologically attractive price point, then they wanna get their drives sold in that segment so maybe cripple some bigger ones down to that. If their defect rate is super low, which is probably most likely at about mid point of a drives market lifespan, then they're crippling perfectly good 10GB drives to have a drive for sale in each segment from 2GB. Howwwwwever... if they really are getting predicted defects and the surface doesn't just have soft errors, but is really no good, then you risk either damaging the heads on a flaky surface by reading higher up the drive, or if a platter was disabled due to a weak head, having half of each read of data potentially being spurious.

Maybe you wanna try this out, here's what I would do to confirm at least short term dependable operation. Actually before you start, see how many errors have been marked in SMART util or similar and whether the error map is full, if it is, forget it, there is going to be errors added, no question, and if there ain't room for any more, the drive is about done already. Format and partition the drive, put basic system files on it to check it's bootable... boot it a few times (remember if a whole platter was disabled, one head may be weak, so system area might not get read right, as now it will be distributed between active heads. If we're good, lets put an ISO of a CD (MSDos 6.22) or a DVD (9x FAT32) on the drive, and copy it to different filenames until you fill up all the new space. Now scandisk and checkdisk it twice... get any errors? You may get a few, the drive may mark some and add reserved area to compensate. Not a worry so far, check SMART, error map full? no? good, continue... delete the ISO and refill drive with a different ISO scan again.... more errors? Okay, that's probably not good now... in particular if you get creeping errors, turn the machine off, the surface is deteriorating... and if it's got that bad, you've only got a 50/50 shot it'll be "okay" if you go back to advertised capacity.

Another thing to worry about is if the drive has temperature compensation values stored for the whole of the maximum maximum capacity, or only the recommended capacity. This will be on a little EEPROM on the controller. If it does not have full disk values, then data written hot on the excess capacity might not be readable cold and vice versa.

Now I've heard it said that retro machine hard drives don't need to be trusted, because you just stick everything on them from your main stash, well yeah, but you prolly don't want to be fighting the drive as much as using it either. If you are in the situation of doing retro development work, or creative work using retro tools, then don't be doing this, you want reliable storage and backup or you'll lose your hard work. Keep this sort of thing for replaceable data.

________ ________ _________

Nobody seems to have mentioned so far the other retro "bigger drive" situations. One is the low level formatting of an MFM drive with an RLL controller, the RLL encoding takes up a third less space for data than MFM coding, so in effect the drive gets 30% bigger, 20MB MFM becomes 30MB RLL or thereabouts. Then there's tricks with higher level software formatting, such as seen on the Win95 1.7MB distribution floppies. This might get you less space lost to the format, but is non standard, so you'll have to have a filesystem driver loaded from a more conventional boot device. i.e. Dorothy is not in FAT 16/32 Kansas any more.

I have that same drive

I did what you said on purpose

Yep bios “reports “ 10gb roughly

Run a disk surface check and everything past 3gb fails.

This seems like a big waste of time to spoof the drive size listed for zero gain and possible data corruption

Boohyaka wrote on 2021-09-08, 17:19:

I believe you are mistaken. It's only they had a single label, and a single manual, for the whole series of hard-drives and capacities, and offered the C/H/S settings on the label for convenience.

correct

maxtherabbit wrote on 2021-09-08, 19:09:

Boohyaka wrote on 2021-09-08, 17:19:

I believe you are mistaken. It's only they had a single label, and a single manual, for the whole series of hard-drives and capacities, and offered the C/H/S settings on the label for convenience.

correct

Double correct.