All depends on time, money and interest.
Something like this I may think, "Could be fun to mess around with for a bit" get the controller, play and sell on. Maybe I'll break even of if I make a small loss I'll put that cost down to the entertainment factor it gave me. but at least you can sell as tested.

If it's something I have no interest in, I'll just sell as untested, even a few dollars is better then nothing.

ALOT of my hardware falls between these 2 groups though. Where I'll say I'll mess around with it and ends up in storage for 10 years and counting and when I do dig it out find it has died while in storage. It's just the risk you take.

These ST412 is 10mb and ST506 is 5MB. Not much to do with it, imagine few 720K floppies on one of these! If I recall correctly both are non-intelligent stepping means the controller card had to manually step through cylinders. Later MFM drives had microcontroller onboard which controller card do is seek from where heads are on to seek 50 cylinders to destination cylinder. command to this drive and drive itself seeks 50 cylinders in one screech.

Cheers,

pentiumspeed wrote on 2022-11-15, 23:55:

These ST412 is 10mb and ST506 is 5MB. Not much to do with it, imagine few 720K floppies on one of these! If I recall correctly both are non-intelligent stepping means the controller card had to manually step through cylinders. Later MFM drives had microcontroller onboard which controller card do is seek from where heads are on to seek 50 cylinders to destination cylinder. command to this drive and drive itself seeks 50 cylinders in one screech.

Cheers,

OP meant ST506/412 interface HD's. The HD's are a ST251 and a NEC D5146 or maybe he meant D5146H)....

Horun wrote on 2022-11-16, 00:48:

pentiumspeed wrote on 2022-11-15, 23:55:

These ST412 is 10mb and ST506 is 5MB. Not much to do with it, imagine few 720K floppies on one of these! If I recall correctly both are non-intelligent stepping means the controller card had to manually step through cylinders. Later MFM drives had microcontroller onboard which controller card do is seek from where heads are on to seek 50 cylinders to destination cylinder. command to this drive and drive itself seeks 50 cylinders in one screech.

Cheers,

OP meant ST506/412 interface HD's. The HD's are a ST251 and a NEC D5146 or maybe he meant D5146H)....

Exactly 😀 yes it is the nec D5146H and st251.

Now I'm trying to get a mfm controller that will work with them. The problem is that there are plenty of overpriced ancient RLL controllers here people try to sell for $100+ with no cables. This is completely silly.

I'm looking for a controller that supports 40mb drives and 5mbit data, rate. If anyone knows any popular models please let me know.

Do not know about data rate but the WD based RLL/MFM controllers are good. One thing you need to know (speaking generally): once you format a MFM/RLL drive from a controller it is tied to that controller so trying to use a different one, even to boot from, will not work.
Is your computer XT 8bit based or 16bit AT/286 based, that is important as to which controller you choose....

Horun wrote on 2022-11-17, 04:04:

Do not know about data rate but the WD based RLL/MFM controllers are good. One thing you need to know (speaking generally): once you format a MFM/RLL drive from a controller it is tied to that controller so trying to use a different one, even to boot from, will not work.
Is your computer XT 8bit based or 16bit AT/286 based, that is important as to which controller you choose....

Yes, I read about this pairing requirement in another thread. It is unfortunate, because recovery of old data is that much more difficult without the original controller.

My pc is an AT 386sx. There is one WD controller I heard it is working (the one with A in its name). That one shows up ocassionally on ebay here in Europe. There is also one DT I know about and that's it. I would be very interested to hear about any other controllers that might be compatible.

I mentioned RLL before, because there seem to be some controllers that support only RLL, while in ST251 driver's manual there is a bit that says "not to use RLL and 5mbit" being a requirement. So one has to be careful to get the right one...

Also, there is a very interesting open source project. A generic mfm reader/emulator. However it is made as an add on for beaglebone single board computer. I have a bunch of raspberry pi's, but no BB and buying one just for this doesn't make sense to me cost-wise.

Does anyone have any documentation for the actual signals and encoding a st412 /ST506 controller has to read ? This is primarily out of curiosity. I don't think I'll put in the time and effort to read those drives (without controllers), but it is an interesting mental exercise.

flynth wrote on 2022-11-17, 09:27:

My pc is an AT 386sx. There is one WD controller I heard it is working (the one with A in its name). That one shows up ocassionally on ebay here in Europe. There is also one DT I know about and that's it. I would be very interested to hear about any other controllers that might be compatible.

The best-known MFM controller for 16-bit AT-class computers is the WD 1003. On ebay Germany, I find 3 offers for a WD1003-WA2 below 35€ including shipping. Two of them "untested/for parts". The cables are nothing special or exclusive. They can be built from off-the-shelf parts today. One is a 34-pin ribbon cable with a 2.54mm-two-way female pin socket crimped at one end, and two card edge connectors (one crimped to the end, one crimped somewhere "in the middle", to connect both drives. The other cable is a 20-pin ribbon cable that is an individual cable for each drive.

The 34-pin cable can be substituted by a standard PC floppy drive cable if you just want to connect one hard drive. Use the card edge connector before the twist.

Tricky business getting old MFM/RLL drives working, I think before even buying a controller card its best to power them up at least once to see if the drive itself is still alive and spins up. Would hate having to find a suitable card only to find out the drives themselves are dead.

If they power up ok and nothing blows on them and you can hear the platters spin up and the stepper try seeking then its a good chance the drive(s) is alive enough to warrant buying a card for it. MFM drives are pretty sturdy but their electronic components are not and tantalum caps tend to throw tantrums the older they get.

If they are dumb dumb MFM drives testing becomes a little more difficult but they should power up and spin up the platters, I cant remember if the steeper will try test seeking without a controller at the very least itll let you know the electronics are stable enough to warrant spending cash on a controller.

Once you do have a controller and can fully test, recover data if possible and low level format them then they should sell rather well as tested working drives. The main issue then is once they are low level formatted youll need to sell them with the controller as a full kit, but that I guess just adds further value.

mkarcher wrote on 2022-11-17, 13:40:

flynth wrote on 2022-11-17, 09:27:

My pc is an AT 386sx. There is one WD controller I heard it is working (the one with A in its name). That one shows up ocassionally on ebay here in Europe. There is also one DT I know about and that's it. I would be very interested to hear about any other controllers that might be compatible.

The best-known MFM controller for 16-bit AT-class computers is the WD 1003. On ebay Germany, I find 3 offers for a WD1003-WA2 below 35€ including shipping. Two of them "untested/for parts". The cables are nothing special or exclusive. They can be built from off-the-shelf parts today. One is a 34-pin ribbon cable with a 2.54mm-two-way female pin socket crimped at one end, and two card edge connectors (one crimped to the end, one crimped somewhere "in the middle", to connect both drives. The other cable is a 20-pin ribbon cable that is an individual cable for each drive.

The 34-pin cable can be substituted by a standard PC floppy drive cable if you just want to connect one hard drive. Use the card edge connector before the twist.

Thanks for the tip about WD1003. I was previously only looking for wd1002. However the one that works is over 50EUR including shipping. That is way too much for an old mfm controller. Looking at sold listings I remember compatible ones going for $10 few months ago.

I'll keep looking.

TrashPanda wrote on 2022-11-17, 14:57:

Tricky business getting old MFM/RLL drives working, I think before even buying a controller card its best to power them up at le […]
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Tricky business getting old MFM/RLL drives working, I think before even buying a controller card its best to power them up at least once to see if the drive itself is still alive and spins up. Would hate having to find a suitable card only to find out the drives themselves are dead.

If they power up ok and nothing blows on them and you can hear the platters spin up and the stepper try seeking then its a good chance the drive(s) is alive enough to warrant buying a card for it. MFM drives are pretty sturdy but their electronic components are not and tantalum caps tend to throw tantrums the older they get.

If they are dumb dumb MFM drives testing becomes a little more difficult but they should power up and spin up the platters, I cant remember if the steeper will try test seeking without a controller at the very least itll let you know the electronics are stable enough to warrant spending cash on a controller.

Once you do have a controller and can fully test, recover data if possible and low level format them then they should sell rather well as tested working drives. The main issue then is once they are low level formatted youll need to sell them with the controller as a full kit, but that I guess just adds further value.

Good Idea. I'll definitely try that first.

So, I've powered up all the drives and ST251 sounds great. However the NEC D5126 (no h in its name actually) sounds a bit strange. It spins up, but as it is spinning there is this quiet sound as if it is catching on something. Then when the stepper motor activates this catching, clicking sound goes away briefly. Then returns. To me this sounds pretty bad. Could someone who knows how those disks are supposed to sound listen to it, please and let me know am I wasting my time with this disk?
Here is the video I recorded just now: https://youtu.be/u4RCwLXT0e0

flynth wrote on 2022-11-17, 21:43:

So, I've powered up all the drives and ST251 sounds great. However the NEC D5126 (no h in its name actually) sounds a bit strange. It spins up, but as it is spinning there is this quiet sound as if it is catching on something. Then when the stepper motor activates this catching, clicking sound goes away briefly. Then returns. To me this sounds pretty bad. Could someone who knows how those disks are supposed to sound listen to it, please and let me know am I wasting my time with this disk?
Here is the video I recorded just now: https://youtu.be/u4RCwLXT0e0

Honestly sounds like it hasn’t been fired up in a long time and the bearing is a little dry, it’s possible it will sort. Itself out after being run for a bit.

The fact it fires up and the stepper seeks is a good indication it’s worth a shot.

TrashPanda wrote on 2022-11-17, 23:02:

flynth wrote on 2022-11-17, 21:43:

So, I've powered up all the drives and ST251 sounds great. However the NEC D5126 (no h in its name actually) sounds a bit strange. It spins up, but as it is spinning there is this quiet sound as if it is catching on something. Then when the stepper motor activates this catching, clicking sound goes away briefly. Then returns. To me this sounds pretty bad. Could someone who knows how those disks are supposed to sound listen to it, please and let me know am I wasting my time with this disk?
Here is the video I recorded just now: https://youtu.be/u4RCwLXT0e0

Honestly sounds like it hasn’t been fired up in a long time and the bearing is a little dry, it’s possible it will sort. Itself out after being run for a bit.

The fact it fires up and the stepper seeks is a good indication it’s worth a shot.

Good stuff. I bid on one controller that should work with it. We'll see if I get it.

I won the auction for an 8 bit data tech 5150x controller. It is only 8 bit, but it is supposed to be compatible with at least st251. So hopefully I'll be able to test the drive properly.

Unfortunately this is an xt not at controller, but I got it pretty cheaply.

Could someone comment on a possibility of using an xt controller on an AT? Are there some software mods? (the controller has socket eprom and I do have a programmer).

flynth wrote on 2022-11-19, 09:58:

I won the auction for an 8 bit data tech 5150x controller. It is only 8 bit, but it is supposed to be compatible with at least st251. So hopefully I'll be able to test the drive properly.

Unfortunately this is an xt not at controller, but I got it pretty cheaply.

Could someone comment on a possibility of using an xt controller on an AT? Are there some software mods? (the controller has socket eprom and I do have a programmer).

It will work out of the box, but it will be slow. XT controllers occupy I/O ports 320-323, IRQ 5 (sometimes jumperable to IRQ2) and DMA3. Make sure these resources are free.

AT controllers will require IO 1F0-1F7, IRQ14, no DMA. Those are the same resources as IDE, because IDE drives behave as-if they were controlled by an AT MFM controller. You don't need a BIOS on AT controllers, as the AT BIOS contains a WD1003 compatible hard drive BIOS, which also is used in case of IDE drives.

mkarcher wrote on 2022-11-19, 10:39:

flynth wrote on 2022-11-19, 09:58:

I won the auction for an 8 bit data tech 5150x controller. It is only 8 bit, but it is supposed to be compatible with at least st251. So hopefully I'll be able to test the drive properly.

Unfortunately this is an xt not at controller, but I got it pretty cheaply.

Could someone comment on a possibility of using an xt controller on an AT? Are there some software mods? (the controller has socket eprom and I do have a programmer).

It will work out of the box, but it will be slow. XT controllers occupy I/O ports 320-323, IRQ 5 (sometimes jumperable to IRQ2) and DMA3. Make sure these resources are free.

AT controllers will require IO 1F0-1F7, IRQ14, no DMA. Those are the same resources as IDE, because IDE drives behave as-if they were controlled by an AT MFM controller. You don't need a BIOS on AT controllers, as the AT BIOS contains a WD1003 compatible hard drive BIOS, which also is used in case of IDE drives.

Wow, thank you very much for the quick answer 😀

It is very hard to find such info online.

In addition, when using an XT class controller on an AT class system, you must set the CMOS setup to "no hard drives"

maxtherabbit wrote on 2022-11-19, 12:42:

In addition, when using an XT class controller on an AT class system, you must set the CMOS setup to "no hard drives"

Thanks. I'll do that. The controller should be arriving pretty soon so I'm starting to think about cables. I noticed fdd cable is 34 pins too. Can I just use an fdd cable with an edge connector for a 5.25in disk drive? Unfortunately all those cables I found so far have the edge connector at the end of the cable where there is a part of the cable turned to allow two floppy drives on one cable. Is this going to be a problem? I could try to modify one of those cables.

Then this leaves the 20pin. I'm thinking of using parts of another fdd cable, but perhaps making a plastic insert into the edge connector to block 14 pins remaining (and cutting the board connector to size).

Does anyone have a better idea?

Yes the twist will be a problem. You can take the back of the card slot IDC connector off and untwist the cable easily enough.

As for the data cable, I just bought 20 pin IDC connectors from ebay and made my own

maxtherabbit wrote on 2022-11-22, 14:49:

Yes the twist will be a problem. You can take the back of the card slot IDC connector off and untwist the cable easily enough.

As for the data cable, I just bought 20 pin IDC connectors from ebay and made my own

I see. The IDC side is not a problem for me, but the other one is a different story (that pcb edge connector). Do you perhaps know a name/type for this connector type?