Low level formatting old hard drives 

As a kid I collected hard drives and loved low level formatting them & mapping bad sectors. I was a weird 10 year old.

This is pure gold, thanks for giving us much detailed information, there’s a lot of confusion on these topics.

I learned this the hard way when i whas young and selling xt class machines. I had a teacher who whas in charge of the informatica systems of that particular school, and he had a room full of xt class machines that wher decommisioned, and since i had a great friendship with this teacher, he told me that those machines needed to be thrown out some day, so i asked if i could sell em, we ended up asking the prinicipal and he said sure, i could keep 1/3th of the selling price per pc, so i got to work, and they all used this kind of hard drive! Its insane how long it took me to figger out how to properly set them up, i ended up selling over 200 pc's for about 5000 belgium francs each (it whas a long time ago), so i made a good amount of money from those machines, i spend HOURES low level formatting xt machines! Insane how long 1 pc could take to format a hdd! How bigger the drive, the longer it takes! I had sometimes 6 pc's in my room all low level formatting at the same time :p insane how the times have changed man! Great video! Love this stuff!

Thanks for the refresher on this stuff. I used to do all of this back in the 80s and had forgotten a good bit of it, but as soon as you mentioned "debug", I then remembered "-g=c800:5". Good times!

Thank you for this video ! Thanks to it I found enough courage to try out my own ST-251 with Western Digital controller, which was laying in box for few years, as I had no clue how to approach it. Thanks to the information from your video and actual parameters for ST-251 from the Internet, it took me about 20min from nothing to booting MS-DOS from ancient hard disk :D

It's always reassuring to see someone doing this with confidence! :-)

My memory back in the day was that we were so happy when an mfm drive would reformat on rll. i ran a seagate 20 meg mfm disk on rll for five years with no issues. I remember lots of drives didnt work and lots did. My seagate was a half height model from about 1987.

It's wild how far computer storage has come since the era of these beasts. My current computer has a 480GB SATA III SSD and it's smaller than even the smallest one of those controller cards, would've been unheard of when these gigantic HDDs were new!

Wonderful video you've really gone through this nicely. I have six MFM's and three RLL's here at home in use in my collection. Really enjoyed this as I've gone through this journey more than a few times over the decades. :)

Thank you so much for this video! This is normally such a murky subject. I have an MFM drive last used circa 1995 and I have been unable so far to properly read the contents to copy them off, after trying 2 different MFM controllers. I can only get a partial directory listing. I think this video plus the heap of various MFM controller cards I happened to pick up lately will enable me to finally read the drive properly. The obstacle, in retrospect of the current retrospect enthusiasm, is that we are used to devices and components being more intelligent, and we don't realize that a few years earlier in industry development, that intelligence didn't exist yet, like IDE drives being able to tell their own geometry to the controller card in in response to a query from the controller card, or actually having a standard mapping for hard drive sectors, like MFM and RLL didn't.

what an amazing walk through - thanks a lot! this is very helpful, and it includes all the details one might need! This is very thoughtful! thanks!

I remember learning the hard way with MRM drives. I use to have 50 of them in a closet waiting to be used. Mom trashed them when I moved out.

Thank you very much for this very informative video!

I totally forgot how I used to do this. Thanks for the refresher. It's only been thirty years? Dang! SATA is a blessing. I see your monitor is as dirty as my test monitors. Great video.

I always formatted my MFM drives with RLL controllers. More space and better speed. Pretty much never used MFM once RLL was available.

is amazing. congratulations!!.

30KB bad sectors when getting 20MB out of 10MB MFM drive seems like a great deal

I have one (MiniScribe Model 3053 assembled in Singapore) & one (model Seagate ST-251 assembled in Singapore) and one large Barracuda that came from my old Dell Computer. Awesome old Computer Harddrives.Also, I have an old (Dec) Digital Celebris GL 6200 with a rebuilt transformer with two large fans in power transformer, and without a harddrive. I have the controller cards. Time to get building now. Thanks ! Awesome video !!

Very cool overview! I also have a large collection of MFM/RLL/ESDI drives and almost all types of 8bit or 16bit controllers. makes a lot of fun to use these from time and remember, what you needed to pay that time. haha!

Thanks to this video i finally installed my old Kalok Octagon, you got a new sub

Hi Thanks for sharing. Excellent guide. I was able to revive my St225 hard drive with Wd1002a controller on old Juko Xt computer. Regards.

"Complex set of commands" that's one term to describe hand writing 16-bit x86 assembly in a REPL...that's actually wild.

Rll encoding was possible on almost all mfm drives. The key to doing it relies on head position accuracy. Some drives were more accurate than others. This gave a lot of rll formatted drives the reputation of being not reliable.. eventually this wasn’t a issue. But the damage was done. The conner drives were great with rll. The rll format gave a good performance increase. A lot of 30mb drives were rll formatted 20mb mfm drives.

I remember sitting down waiting for drives to format, and later on waiting for them to defrag lol. Things have come a long way in terms of speed, but these were so quick compared to floppy disk's and MS DOS use to load in seconds off an MFM drive.

I just got my first MFM drive from the dumpster, so I will use this to Low level format them.

Bad sectors on these drives are common from the factory. What you do have to watch out for buying second hand are lots of additional hand scribbled bad sectors, one or two is fine, but I've seen drives with multiple post it notes full of bad sectors listed.

I am another who used to Low level format MFM hard disks with Norton Utils Calibrate to make it run faster by changing the interleave of the disk. No one low level formats hard disks these days but it's equivalent is zero filling hard disks.

This 8bit ISA era of computing is special, a scene onto itself compared to the later more powerfull dos machines of the mid 1990s. I especially like the Zenith data systems PC clone for their inner architechture. it is also exciting to know tha tnew 8bit ISA cards and CPU boards are being made from scratch once again. one could build an 8bit 8088 pc clone from all new parts, maybe except genuine drives.

Cool. Learned a bunch. I have a number of mfm drives that need attention. Did not know these specifics. They probably won't work anyway but I can test them better anyways.

The later 16-bit WD controllers were pretty much exchangeable. I have 3 different WD MFM controller cards and I can use my SD-251 disks with any of them, without the need of LLF.

interesting! It drove me back in the days... :)

Can't wait for the video on ESDI drives.

How did I kmow about MFM in 1995? The era of IDE. I was just playing with CD's back then.

Brings back memories, also there was some utility that could dynamically test and optimize the interleave - I think you need more than 3 on a slow PC XT ... interleave too low and you end up with 1 sector transferred per revolution, too high - well, interleave neds up being the number of revolutions needed to read the whole track. Interleave 3 means that the track numbering skips 2 sectors and warps around 3 times, so the controller has two sector times to finish transfer and be ready for the next sector

Ah! That explains quite a few things

Great Video. MFM-RLL has to do with the Harddisk magnetic disk capability. See as Single Density and Double Density. RLL is more dense in magnetic particles. That is what I read about RLL. So only If you have luckily a very good production MFM drive it can in RLL mode, But as you experience in your vid. Lot of bad sectors or hard time to get it formatted and an indication that it will also have hard time to put data on it reliable. An indication is the list of bad sectors on the disk-label, or imperfections of the magnetic layer it is at the start.

Try again the adaptec ABC-2072 controller using custom LLF on the so called MFM drive. Whilst giving it a propper step rate (i.e. option #5 which, if I recall corretly, means 70 micro seconds) it will allow the heads to settle a bit and will results in a working LLF. I used this on an ancient Control Data WREN drive which is called MFM type, and it worked fine. In fact, there is no MFM or RLL drives, they just needed to become better in mechanics manufacturing and physics.

Where can I get that software for my XT clone ?

Interresting video ,wish i had known all these back then -Nowadys I just despise microsoft for what they did to windows but i guess marketpeople jacked it.

Nice video ! I have an IBM 5170 with 20mb double height MFM seagate - still works!

Most Micropolis or Maxtor MFM drives would format out as RLL with no issues. Lots of models of Priam and Rodime would handle it too. Connor and Seagate, forget it. Anyhow, I moved onto ESDI drives because despite their full height I wanted the capacity (at a cost) but I was doing work that paid for such an expense, so no bother.

Z80!!! Legendary microprocessor!!!

Great to see all the old hardware again Great days Do you have a bbc torch in your collection ???

How do you know which controller is MFM and which is RLL? I want to buy such controller but i cant find info about it if its MFM or RLL.

Another way to low level format and set the interleaving was to use the Norton Utilities Calibrate program.

Very interesting video! Could you do a video on old hard disks with issues? Is there a way to bring them back to life? I have a few old hdd's laying around. Usually when I restore a pc I replace the hdd with an industrial IDE flash drive. But I leave the old disk in to keep it complete. These old disks usually don't work anymore. Either there's a mechanical sound of they are not detected by the BIOS. And I really don't know what to do with these old hdd's. Googling on this topic brings up loads of recovery tools and businesses which can recover your (modern) hdd data. So finding the right search terms is difficult. Do you have any suggestions?

When you're out of touch: 20:12 asks for y/n types in Yes.

Interesting retrospective, watching this on a system with 18 TB of storage.

I actually have a copy of the book hard drive bible that covers a lot of the rll, mfm, ide, and early sata! Dam thing is about 2.5” thick loaf

What camera are you using? :O

That's a neat collection of MFM hdds ! My 286 has a 40MB seagate which is connected to a 16 bit ISA controller. These don't need a bios since the computer's BIOS sets the CHS settings, so I guess that technically this computer could use any of these drives, right ?

Sir, can I test this type old Hard-Disk by just connecting the power plug?

I fornat low level to many HDs, good results! SINCE 1985

Wish I could find a BASF drive like that, they're very uncommon in the USA.

New sub here ;)

Commodore 64s I believe had either MFM or RLL floppy drives. A PC floppy drive can not read those (I tried).

I had a WD1002 with a fixed BIOS in a Commodore PC-10. Some kind soul had actually dumped the SuperBIOS ROM on the web several years ago... I was able to burn it to an EPROM and use the card again with an ST225 when the original Microscience 10MB drive died.

low tech rocks!

I once had a computer with an 80 MB drive. The odd thing was I could only get 60 out of it. I am not sure what was happening. Maybe it was a loss from formatting? A controller for a similar drive of lower capacity than what I had? I always thought it was weird.

What happend go c800:5000 adres to init low level format routine? Ah, ok its at 15 minutes and apparently my memory is also corrupted.

I've owned most of the drives at one point.

Now you can find a micro SD memory of 500Gb

@ 0:23 - ST-412 MFM - now i am curious

Great information, way to slow video though. Keep having the same problem with a lot of channels about computers. Unless I really want to learn some stuff beforehand, I'm not intrigued by the video pace.

Today there is no real low level format anymore. HDGuru's "Hard Disk Low Level Format Tool" is also not a real LLF. Or? Is there still software that can run a real LLF? With reallocation of sectors.

12:27 thats what she said... sorry

11:55 "a very complex set of instructions" ... that is literally 5 assembly instructions. Even a basic Hello World program takes more instructions than that! I don't see how this can be described as complex?

If you're ever interested in selling that BASF mech for any price, send me an email!

imagine 3.5'' ssd and 5.25'' ssd the bigger one would be around 40tb

Time for somebody to create the mother of all hard disk controller cards.

Not exactly true A harddrive low level formatted on an older tech controller will work fine on a newer card without reformatting. Or at least it should. You can take a pcAT mfm and stick it on a VLB mfm ( the very last generations of mfm) controller and read and write just fine.

dee

11:50 you are programming in assembler mate! those are not "commands"

You did all that for 90 MBs of storage? Why that's just stupid the hatd drives belong in the trash. A micro sd has more storage. Hell a zip drive has more room.