For the system the MFM/RLL controller looks like an IDE controller. It uses the same port and IRQ address scheme.

The straight way is to use the MFM/RLL controller as primary one (with IRQ14), and to disable the primary IDE controller on the mainboard.
So you just use the secondary IDE controller (with IRQ15) from the mainboard.

There is no primary ide controller on the Mainboard, only floppy (see edited entry posts last paragraph)

It's particularly on, how to get them side by side running.

Therefore, I 'm trying to get the IDE/FDD/Multi IO cards working in irq15 instead. I think, disabling primary and enabling secondary might do the trick, but I'm not sure.

Aldo, I'm absolutely not sure, if the BIOS will support it anyway, because it got only two HDD entries which are selectable by HDD types and two (type48 and 49) for custom settings, which I need for all my MFM HDD and CF Card also.

But I also read on a driver for a third or fourth drive, and hdsniff lists both, but dos cannot see it and gives no drive letter. So maybe I should give that driver a try?

I doubt, that I can select master/slave in bios and adjust the dip of the working NEC D5126 to 2 instead of 1 for slave or vice versa the CF Card as slave on two different channels (Irq14 and irq15). But the issue is, I'm not sure at all with all of my hypothesis and guesswork.

I want also learn something on this.

Then you need a pair of MFM/RLL and IDE controllers which can coexist. One has to be capable to run as secondary and on IRQ 15.
But, wait. If you have such an old motherboard, it probably won't have BIOS support for the secondary controller at all.

If you plan to not use any HDD on a secondary IDE controller, you don't need to care much about BIOS support. CDROM and ZIP drives have their own driver support.

So the only solution in my case, where hdsniff can report on two drives (but it retrieves the information on CHS from my BIOS entries for both drives?? that came suddenly to my mind ..), that I use the 3drive driver I think, like an iomega zip drive driver or CD-ROM driver, right? http://oldcomputer.info/hacks/4hdd/index.htm

Could you post a picture of the mfm controller you are using ?

No. I tried Saturday and today to upload Fotos. It uploads just fine, but then submit is greyed out.

One question is still somewhat unanswered. To make it sure:
Primary is synonym for Irq14
Secondary is synonym for irq15
on ISA systems without irq sharing, right?

Iarsin wrote on 2023-04-10, 11:37:

No. I tried Saturday and today to upload Fotos. It uploads just fine, but then submit is greyed out. […]
Show full quote

No. I tried Saturday and today to upload Fotos. It uploads just fine, but then submit is greyed out.

One question is still somewhat unanswered. To make it sure:
Primary is synonym for Irq14
Secondary is synonym for irq15
on ISA systems without irq sharing, right?

Did you select the license type for the photo you uploaded ?

also, primary & secondary irqs for IDE are indeed 14 & 15. not so for mfm.

So I can set the ide to secondary=irq15 to solve the irq conflict.

I looked, and cc was checked.

It came to my mind to upload some Foto to drive.

Running scandisk on NEC D5126 MFM drive.
https://photos.app.goo.gl/X6vEfusrpfYjU9e97

Six Mio cards
https://drive.google.com/file/d/1YrC64Z6X6e0F … ew?usp=drivesdk

Setup
https://drive.google.com/file/d/1Yu_qwghnyfT3 … ew?usp=drivesdk

Cabeling, on the left side you can see the Unisys wd1003V-MM1 is lacking a FDC, due to avoiding conflicts with the onboard FDC. I guess Unisys (multitech/ later Acer) modified the WD controller that way to fit into their system and maybe to make it cheaper?
https://drive.google.com/file/d/1YuMnx1qhk4tX … ew?usp=drivesdk

Unisys WD1003V-MM1 Label
https://drive.google.com/file/d/1YtUgqecVrbyf … ew?usp=drivesdk

I looked up the card WD1003V-MM1 and found a photo of the backside on ebay.
The only IRQ lines in use are 6 and 14, 6 is for the, in your case non-existent, floppy, and 14 should then be for the hard drive controller.

so, yes, disabling primary ide and using the secondary should prevent conflict.

weedeewee wrote on 2023-04-10, 11:48:

Iarsin wrote on 2023-04-10, 11:37:

One question is still somewhat unanswered. To make it sure: Primary is synonym for Irq14 Secondary is synonym for irq15 on ISA […]
Show full quote

One question is still somewhat unanswered. To make it sure:
Primary is synonym for Irq14
Secondary is synonym for irq15
on ISA systems without irq sharing, right?

also, primary & secondary irqs for IDE are indeed 14 & 15. not so for mfm.

Not for for XT MFM controllers. They typically use IRQ 5 (primary) or IRQ 2 (secondary). But very much so for AT MFM controllers. Primary and Secondary mean a combination of base I/O address and IRQ number. Primary means IO port 1F0 (and 3F6) combined with IRQ14; Secondary means IO port 170 (and 376) combined with IRQ15.

Even with no mainboard BIOS support for a secondary IDE controller, you can use the secondary IDE controller if you install a ROM extension that provides a replacement for the mainboard integrated IDE BIOS. A widely used open-source enhanced IDE BIOS is the "XT-IDE" BIOS, which can be programmed into a ROM chip that gets installed on a network card instead of a boot ROM. You likely need to configure the XT-IDE ROM to use a fixed geometry on the MFM drive. The "IDE identify" command is not supported by an MFM/RLL controller.

So to combine IDE and MFM hard drives in an AT, I recommend you to

• Use a IDE interface / multi I/O card that is able to be configured as secondary card (1F0 / IRQ15). A IDE CD-ROM will do, too.
• Configure XT-IDE with the C/H/S parameters for "primary master" matching your MFM drive.
• Write the configured custom XT-IDE ROM image into a UV-erasable EPROM or flash EEPROM chip that is compatible with the network card you intend to use.
• Enable the boot ROM on your network card (using jumpers or the setup tool)

You can skip all this stuff, though, if you do not run hard disks on your secondary IDE channel, but CD-ROMs and ZIP drives only. Those drives do not need BIOS support.

Thank you all, I can try the XT IDE approach. I'll compile it on my notebook and use a floppy instead with optromloader to use the XT IDE. I see, if I can configure the primary with the c/h/s "hardcoded" in the XT-IDE optromloader floppy.

Beside that, I maybe try the driver approach of 3/4drives as I linked above, first.

So looking for an IDE controller which will be good as a secondary channel, you have to find one which has "master/slave" jumper […]
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So looking for an IDE controller which will be good as a secondary channel, you have to find one which has "master/slave" jumpers (they usually switch address, sometimes IRQ) or address selection jumpres and IRQ14 disabling jumper. However, it is theoretically possible to force controller card to not work in IRQ14 by disconnecting IRQ14 pin of ISA bus - for example by a piece of sticky tape, but I've never tried it!.

If you set up your card an plugged it in, it's time to install the hard drive(s): They must be already partitioned (the driver works with one big primary partition for one drive) and formatted using another computer with the same version of MS-DOS. Install the drive(s) in your PC as usual connecting them to the secondary card.

You won't see these drives in DOS or FDisk now. But let's test are they visible in computer's memory: Download this pack of tools:

4 HDD Utilities disk

And run WDTBLCHK.exe If your IDE drives aren't visible in DRIVE 3 and DRIVE 4 in one of tests, something is wrong.

http://oldcomputer.info/hacks/4hdd/index.htm

Hm, I got two different version of msdos on the drives. 6.22 on the MFM drive and 4.01 on the CF card ... So maybe XT IDE is the way to go.

Hopefully I can manage to configure at least one of the bunch of IDE multi I/O cards for secondary/irq15 and it will neither conflicting nor be defective.

Thank you for particulary sorting out my unsure understanding or misunderstanding on addressing those controllers.

One question comes to my mind, because I got a fifth MFM drive, I didn't tested, because it was cut off the Molex 4-pin power conection. It's a Tandon 282 with a 382 PCB.
The power cabling color code is different to ATX Molex (red, black, black, yellow) I don't know which of the (blue/purple, red, white and grey) cables should I solder to what color of the YBBR AT/ATX Molex.

Also which kind of oil to use for sticking stepper motors. Sewing machine oil?

Iarsin wrote on 2023-04-10, 12:50:

One question comes to my mind, because I got a fifth MFM drive, I didn't tested, because it was cut off the Molex 4-pin power conection. It's a Tandon 282 with a 382 PCB.
The power cabling color code is different to ATX Molex (red, black, black, yellow) I don't know which of the (blue/purple, red, white and grey) cables should I solder to what color of the YBBR AT/ATX Molex.

Originally, it likely looked like this: https://upload.wikimedia.org/wikipedia/common … don_HDD_MFM.jpg , with no Molex connector at all. Likely, your hard disk PCB has a couple of DIP chips. Most of them have the power supply pins at the common location, with GND at one corner and +5V at the opposing corner. If you put a chip in front of you with the Pin 1 marking to your left, and one row of pins facing towards you, the rightmost pin on the side facing you is usually GND, and the leftmost pin on the side facing away from you is +5V. You should be able to use continuity measurement to find GND (hopefully twice) and +5V on the power cables. The remaining cable is +12V.

Iarsin wrote on 2023-04-10, 12:50:

Also which kind of oil to use for sticking stepper motors. Sewing machine oil?

Sewing machine oil will work fine.

Is black and white on the downside connected to the same pin for gnd? So that grey and blue is either -5V or 12? Ok, I'll have a look at the PCB, and on one video of Adrians basement, I think I saw such different color code with Molex 4-pin connectors connected.

Ah, it's really about choose a license. But I remember that cc was already selected as only option the last time? Bizarre.

Iarsin wrote on 2023-04-10, 16:53:

Is black and white on the downside connected to the same pin for gnd? So that grey and blue is either -5V or 12? Ok, I'll have a look at the PCB, and on one video of Adrians basement, I think I saw such different color code with Molex 4-pin connectors connected.

Ah, it's really about choose a license. But I remember that cc was already selected as only option the last time? Bizarre.

Black & white connected is possible.
It looks like it is even marked on the pcb +12v = blue , so red = +5v
You mention -5v in your comment. IT IS IN THESE CASES NEVER -5v !
Also you mention grey. I don't see any grey wire

Iarsin wrote on 2023-04-10, 16:53:

Is black and white on the downside connected to the same pin for gnd?

That's likely. If you don't have a multimeter yet, get one to do continuity testing. For casual work on low voltage systems, like PCs (not including the power supply), the cheap 10€/10$ stuff should be good enough. With a multimeter, you can test continuity between black and white to be sure.

Iarsin wrote on 2023-04-10, 16:53:

So that grey and blue is either -5V or 12? Ok, I'll have a look at the PCB,

Looking at the PCB is actually a very good idea: Did you notice the print "+12V" next to the blue wire?

So the answer is: blue: +12, white and black: GND, red: +5V (it looks like it might say "+5V" partly hidden by the jumper pins "W3").

Looking at the PCB is actually a very good idea: Did you notice the print "+12V" next to the blue wire?

No, I didn't noticed that. Thanks to point that out. Okay -5V wasn't the right current. I'm not very familiar with circuits and electronics.

Okay, "grey" is indeed black.

Here is the picture of the video of Adrians basement.

1  R  Bl W  B
2_____________
3| o  o  o  o |
4\____________/
5
6  R  Bl Bl Y
7
8XT/AT   |   ATX
9Red    -≥ Red     +5V
10Black  -> Black   GND
11White  -> Black   GND
12Blue   -> Yellow +12V

I managed to attach theCF card by using the longshine LCS 6624 G. I thought it doesn't support irq15/secondary preferences, but I finally figured out how to do it, and it worked. Unfortunately two other cards seem to be broken. The esio v1.1 didn't work.

I then controlled by floppy boot with the 4hdd image floppy and using wdtblchk, which showed the CF card.

Then I installed the 3drives.hdd and everything went fine.

So I assume, it also would work with XT-IDE, but I don't have the time this week, to compile and configure it.

Bizarre is, that all diagnostics utilities come with irq15 is free and unused. Doesn't understand that.

Challenging was to find all the documentation, and understanding the different schemes for explaining the jumper settings in the documentation. Also there are sometimes differences to the current revision of a card.

Then my other issue with the conflicting floppy controller and probably defective IDE cards.

Also some misunderstandings stood in the way.

So thanks a lot for your help!

Hi there!

The main problem is this, as far as I understand.

a) both IDE host adapters ("IDE controllers") and the "AT Fixed Disk Adapter" use same resources

b) The PC/AT BIOS doesn't boot from Secondary Master at 170h (rather just Primary Master.

c) The Multi-I/O ISA cards provide an Primary IDE port only

To solve this issue, a) an XT MFM/RLL Controller could be used - if it's on-board BIOS can coexist.

Or b), that IDE via Secondary Master is used. That requires a non-Plug&Pray soundcard with a hardwired IDE ATAPI port, which is normally configured for 170h (good).
- Or one of those very small/short IDE/ATAPI CD-ROM interface cards with a 3,5mm jack for audio pass-through.

In addition, XTIDE Universal BIOS or an EIDE Enhancer BIOS must be used.
XUB can boot from a soundcard port, if properly configure through its DOS utility (must be used! XUB images for download lack a valid checksum).

Edit: What comes to mind: IDE devices like HDDs and CF cards are backwards compatible to IBM's AT Fixed Disk Adapter, both use WD1003 language as a basis.
However, they're not identical. Early versions of OS/2 (say v1.2/v1.3) have compatible issues with IDE. They hang during boot.

Advanced things like auto-detection can't be used with an AT Fixed Disk Adapter (or clone) yet, of course.
That feature simple isn't implemented on the big ISA board with the Western Digital controller chip. It's implemented in the firmware of IDE HDDs and CF cards, by contrast.

Then, there's the issue with ATA-2, which changed some bits.
https://www.os2museum.com/wp/how-to-please-wdctrl/

That's why mixing ancient IDE HDDs and CF cards on same 40pin cable can cause trouble, I think.

Pictures of the IBM Fixed Disk Adapter: https://minuszerodegrees.net/5170/cards/5170_ … rds.htm#fddda_1

Edit: More information: https://forum.vcfed.org/index.php?threads/wd- … e-xt-mfm.41883/

WD1002 and WD1006 are also relevant.
They're related to WD1003. For simplicity, I just say "WD1003". It's a safe bet, so to say.

It would be much easier when you could use another motherboard with integrated IDE controller which is able to deactivate primary IDE and to boot from secondary IDE.