ST-412 MFM HDD / CARD possible IRQ 5 Issue with 80286 mainboard

[_ds_]

Hi all,

I think I am running into an IRQ conflict with my ST-412 MFM Disk and Card.
What I see out from some manuals, the ST-412 card assigns IRQ5. (https://nerdlypleasures.blogspot.com/2016/05/working-with-st-506-interface-mfm-hard.html)

See ST505 Chapter, 3rd paragraph.

The IBM PC and XT BIOSes do not support hard drives and know nothing about them. Support is added via a BIOS extension found on a hard drive controller card. The default settings for XT controller cards are I/O 320, IRQ5 and DMA3. An alternative I/O setting is at 320 and some cards allow the IRQ to be set to 2. The latter is necessary when using an MFM controller in a Tandy 1000, which uses IRQ5 for video (Ghostbusters will not work properly if IRQ5 is disabled for video, as it can be on the SX and TX). The controller's BIOS extension also provides hard drive tables for the types of hard drives it supports.

IRQ5 is per default assigned on 80286 mainboard to LPT2 or LPT3 (https://en.wikipedia.org/wiki/Interrupt_request)


Is there any way to solve it?

My symptoms are, that the card wont be initialized and therefore also no "red" led flashes on the MFM HDD.
So the HDD is not recognized

BR
Dieter

 

[_ds_]

here some additional screenshots out from diagnostic tools like "SYSINFO" and "CHECKIT"

 

[kb2syd]

Unless you have a device already installed using IRQ5 then the it will be available for the hard drive controller. Specifically, what is the manufacturer, model number and part number of the controller card you're trying to use?
What motherboard are you trying to use the card in? 5150? 5160? Clone?
What other cards do you have installed? IRQ 5 isn't 'reserved' for anything. It's available for use until you physically install an expansion board that expects to use it.

 

[_ds_]

There are no other cards present in the Isa slot since I have just one.

I am going to use the IBM 6135984 MFM controller card.

Regarding motherboard I have no idea. I think it’s type AT

Here few fotos of drive and card as also mainboard

 

[kb2syd]

Go into the BIOS setup, set the built in IDE to secondary and set it as disabled. Disable all other motherboard hardware you're not using.

Something is getting in the way of the option rom loading.
The controller looks like variation 2 of the IBM Xebec controller here: https://minuszerodegrees.net/ibm_xebec/ibm_xebec.htm

 

[_ds_]

Unfortunately I have a minimalism BIOS.

I could disable (not installed) both floopy drive and set the C Drive to not installed but how should I configure then the D drive?

 

[kb2syd]

If you can't disable the primary IDE interface then this board will not work for you. As it is, since this is an 8 bit controller, you would have to set both to disabled/not installed and let the BIOS for the Xebec card load.

 

[_ds_]

If you can't disable the primary IDE interface then this board will not work for you.

The only thing what I could do is setting C and D drive to „not installed“
But there is no option regarding primary / secondary

 

[kb2syd]

I don't think this motherboard/controller combination is going to work for you, unless you have all the jumpers and one of them allows you to disable the IDE controller on the motherboard.

 

[modem7]

I don't think this motherboard/controller combination is going to work for you, unless you have all the jumpers and one of them allows you to disable the IDE controller on the motherboard.

I expect the situation to be similar to [this] - no hardware conflicts between the two different hard drive controller types.

The hard drive type numbers in CMOS SETUP would be set to 0 or 'none' or 'not installed' (etc.), because there are no attached IDE drives for the motherboard's BIOS to manage.

My symptoms are, that the card wont be initialized and therefore also no "red" led flashes on the MFM HDD.

But maybe the MFM controller is in fact being initialised. The symptom of 'Not seeing expected LED flashes on the MFM HDD' has many possible causes.

Is your {MFM controller + MFM HDD + cable set} combination known to be a working combination - you have that combination working elsewhere ?

The MFM controller is an IBM Fixed Disk Adapter. With that controller, it is known that the initialisation code in the controller's BIOS ROM will generate an on-screen 1701 error if the code does not see the HDD reporting as 'ready' within about a 20 second period (i.e. an about 20 second timeout). And so, if you disconnect the HDD from the controller, do you see a 1701 error at power-on time?

 

[kb2syd]

I expect the situation to be similar to [this] - no hardware conflicts between the two different hard drive controller types.

The hard drive type numbers in CMOS SETUP would be set to 0 or 'none' or 'not installed' (etc.), because there are no attached IDE drives for the motherboard's BIOS to manage.

Thanks for clearing this up. I know I had problems with 16 bit MFM controllers and IDE contollers being installed at the same time but wasn't 100% sure how the 8 bit controller would work in the 16 bit environment. I know that it has it's own BIOS and needed the drives set to none

 

[modem7]

I know I had problems with 16 bit MFM controllers and IDE contollers being installed at the same time ...

Expected, because:
- a 16-bit MFM controller is an AT-class MFM controller, and
- in the move to 16-bit IDE/ATA, the AT-class MFM controller functionality was relocated into the drive (motherboard still sees a 16-bit MFM controller).

 

[_ds_]

And so, if you disconnect the HDD from the controller, do you see a 1701 error at power-on time?

Not at all. I don’t geht any of these error in in BIOS C and D drive are set to „not installed“

 

[modem7]

And so, if you disconnect the HDD from the controller, do you see a 1701 error at power-on time?

Not at all.

A faulty IBM Fixed Disk Adapter is a possibility. (You didn't answer my, "you have that combination working elsewhere?' question.)

Before going down the 'the BIOS expansion ROM in the IBM Fixed Disk Adapter is not being executed' path, we should verify that the subject ROM is actually appearing in the computer's memory space. I see that you have CheckIt 3. In CheckIt 3, do you see the IBM Fixed Disk Adapter's ROM (resides at address C8000) when you use the menu path of: {SysInfo}{Memory Map} ?

If so, you do have 'take that with a grain of salt.' I could probably put any BIOS expansion ROM there, and because it resides at C8000 (sometimes indicated as 'C800' or 'C800:0'), CheckIt will consider it a "Disk ROM". And I doubt that CheckIt will verify the 8-bit checksum of the applicable area of a BIOS expansion ROM.

 

[modem7]

Using DEBUG is another 'gaining confidence' thing, as shown below, looking at the first 128 bytes starting at address C8000.
Per [here], the first two bytes are 55 and AA, an indicator of a BIOS expansion ROM.

 

[_ds_]

A faulty IBM Fixed Disk Adapter is a possibility. (You didn't answer my, "you have that combination working elsewhere?' question.)

Yes it was working. The seller demonstrated it before I bought it.

do you see the IBM Fixed Disk Adapter's ROM (resides at address C8000) when you use the menu path of: {SysInfo}{Memory Map} ?

No nothing

Using DEBUG is another 'gaining confidence' thing, as shown below, looking at the first 128 bytes starting at address C8000

Same with debug.
The whole content seems to be empty with FF

 

[modem7]

No nothing

Same with debug.
The whole content seems to be empty with FF

Card known to be functional. So the question now becomes, "Why isn't the card's BIOS ROM appearing in the 286 motherboard's memory space?"

Rhetorical: Is the ISA slot too fast for that card (a card designed for XT-class machines).
Rhetorical: Is the problem mentioned in post #8 at [here] in play?

 

[_ds_]

On eBay I found for less money this controller.

WD1003-WA2 Hard Drive Controller - Peripheral - Computing History

The western Digital WD1003WA2 controller interfaces with up to two Winchester ST506ST412 hard disk drives and up to two floppy disk drives in an IBM PC AT or compatible system.The western Digital W...

www.computinghistory.org.uk

What is your opinion? According to this website an AT mainboard should be supported. maybe better as my current ( I think an XT controller ) controller is compatible with my 80286 AT mainboard.

 

[modem7]

... as my current ( I think an XT controller ) controller ...

The IBM Fixed Disk Adapter is definitely an XT-class controller. It was the MFM HDD controller supplied by IBM in the IBM XT. That doesn't mean that it will not work in an AT, but some AT-class machines are going to be problematic for the IBM Fixed Disk Adapter.

Looking back at post #6, have you experimented by turning off ROM shadowing (just in case), and turning off 'Power on high speed'? With the hard drive disconnected from the IBM Fixed Disk Adapter, expected is a 1701 error appearing after a timeout of about 20 seconds.

On eBay I found for less money this controller.

What is your opinion? According to this website an AT mainboard should be supported.

I see, "drives in an IBM PC AT or compatible system." Western Digital and the like often gave themselves the "or compatible" out, because obviously, they cannot guarantee operation in all clones.

You certainly have a better chance of getting that MFM controller card, an AT-class controller, operating. And, I don't know if performance is important to you or not, but that card, being 16-bit rather than 8-bit, will perform better.

Maybe get assurance that you can return the card if there is a problem.