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View Full Version : Seagate ST 4096 and National Computer NDC5445



Amakira
September 11th, 2017, 04:36 PM
I have a Seagate ST 4096 and a floppy drive both connected to a NDC5445 controller card that i'm trying to get fully working.

The drive powers on and has no noticeable problems but i get a "HDD Controller Failure Press <F1> to Resume" which then the machine will boot the floppy. I then tried to low level format using debug but when enter the address G=C800:5 nothing happens and i have to reset the machine. Is there a problem with the HDD, a problem with the controller or something i'm not doing correctly?

modem7
September 13th, 2017, 02:16 AM
Welcome to these forums.


I then tried to low level format using debug but when enter the address G=C800:5 nothing happens and i have to reset the machine.
Note that the G=C800:5 method is only applicable to some controllers, not all.


... connected to a NDC5445 controller card
I cannot find any information on this card. Are you able to post a photo of the card ?


... but i get a "HDD Controller Failure Press <F1> to Resume"
Is the computer an XT-class computer or an AT-class one ?

Does the same message appear if the controller is removed from the computer ? I am trying to ascertain if message is generated by the computer or the controller.

Too early to tell, but one possibility is that you have an AT-class computer that is looking for an AT-class HDD controller, but not finding one because the fitted controller is XT-class.

Amakira
September 13th, 2017, 11:19 AM
This is the controller card. 40730 I managed to miss spell it as NDC5445 instead of NDC5425, my bad thats why you probably couldnt find anything on it.

Both that card and the drive came out of a nonfunctional 386 and connected to a functional 386.

Without that card installed the computer gives the same HDD controller failure and also FDD controller failure, only the FDD worked fine attached to the card.

I also tried to use the card and drive in a 286 but the same FDD didn't work at all attached to that card, if the FDD was connected to the motherboard FDD controller it would function but not boot. As soon as the controller card is removed will the FDD function and boot.

modem7
September 13th, 2017, 04:46 PM
I managed to miss spell it as NDC5445 instead of NDC5425 ...
I cannot find the manual. They normally contain lots of information.

The norm for an AT-class HDD computer is shown in the bottom half of the diagram at [here (http://minuszerodegrees.net/hdd/HDD%20controllers%20-%20XT%20versus%20AT.png)]. No BIOS ROM on the controller, with HDD related BIOS requests handled by the BIOS on the At-class motherboard.

Your NCL5425 has a ROM, the TMM24128 chip. Sometimes a ROM supports a microcontroller, but the fact that there is a drive table at the bottom of [here (http://th99.classic-computing.de/src/c/M-O/20150.htm)], suggests instead that the ROM is a BIOS ROM. If that is the case, then your controller is just like a 16-bit SCSI controller - it has a BIOS ROM. The manual possibly instructs the person installing the controller to set the hard drive type in the AT-class motherboard BIOS to 0 (or 'none'). In that way:
1. The BIOS on the AT-class motherboard knows that it is not expected to handle HDD related BIOS requests (and consequently will not try to communicate with a 'standard' AT-class HDD controller); and
2. When the AT-class computer is powered on, the BIOS ROM on the NCL5425 will kick-in to handle HDD related BIOS requests.

Maybe someone with a NCL5425 will confirm/deny.

Just in case of a poor electrical contact, try removing the controller's TMM24128 chip, then replacing it.


I also tried to use the card and drive in a 286 but the same FDD didn't work at all attached to that card, if the FDD was connected to the motherboard FDD controller it would function but not boot. As soon as the controller card is removed will the FDD function and boot.
No doubt, the resources (see [here (http://minuszerodegrees.net/misc/resource_conflict.png)]) of the controller's FDD circuitry and the motherboard's FDD circuitry are the same. They will conflict, just like two people trying to drink the same glass of water.

Stone
September 13th, 2017, 05:17 PM
The HD's geometry doesn't match any of the HDC's supported drive types.

modem7
September 14th, 2017, 01:55 AM
The HD's geometry doesn't match any of the HDC's supported drive types.
Maybe the drive was being used at reduced capacity.

However, I have just noticed that the drive table shown in TH99 exactly matches the first 15 types in the IBM AT. Therefore, considering also that the vast majority of AT clones use the same 15 types as the AT, what would be the point of designing a BIOS ROM into this "MFM" controller ?

Maybe the drive table in TH99 is a red herring, and the NCL5425 is a 'classic' AT-class HDD controller.

Amakira
September 14th, 2017, 10:19 AM
I tried reseating the controllers rom and changing some jumpers and cables around according to what i read in the CSC Hard Drive Bible and now i'm actually able to read the disk. It showed as only having around 3MB in capacity but when reformated it came up as the full 80MB. Scandisk also said that it detected physical damage so i hope this drive isnt going die right after i got it all working again.


The manual possibly instructs the person installing the controller to set the hard drive type in the AT-class motherboard BIOS to 0 (or 'none').

The drive type had to be set to type 35 on the motherboard bios in order to read the disk.