5150 DRDOS vs MS/PCDOS HD Setup

[Andrettigto]

My hair's thinning as I get old and this last experience hasn't helped any...

I'm been setting up a 5150 Rev.A (updated BIOS) installing an ST225 and WD1002A-WX1 controller. I ran into issues under both DRDOS 5.0 and 6.0 where, after creating the partition, making it active, formatting and transferring the system files, it would not boot. From a floppy boot, I could access the drive and verify the files. My original intention was to use DRDOS as I've always favored it and use it on my other systems. After the install failed under 5.0, I repeated it again using 6.0 with similar results.
This was really confusing since, on my other 5150, I use a WDXT-GENII PLUS and during POST, it displays a message showing "# Hard Drives". The WD1002A-WX1 displays no BIOS messages during POST and being unfamiliar with the card, I started overthinking it. It seemed like the drive wasn't being marked as active.
Finally later in the week, I redid the install using PC-DOS 3.3 and, with no issues, it booted from the Segate.

Strange but true! I don't understand it but glad it's resolved. Now I'm wondering if all the failed CF card attempts I've had are related to this since the system I used creating them runs DR-DOS.

 

[Hak Foo]

Don't the "generic" MFM controllers have to record disc geometry somewhere? Maybe it's recording them in a spot on disc that clashes with the DR-DOS boot record?

 

[Eudimorphodon]

Don't the "generic" MFM controllers have to record disc geometry somewhere? Maybe it's recording them in a spot on disc that clashes with the DR-DOS boot record?

So far as I’m aware the controllers that do that steal a whole cylinder of the drive to stash the information and subsequently lie about the count, so the only way DOS could overwrite it is if it banged on the hard disk controller chip’s registers directly. So I doubt that’s it.

 

[Andrettigto]

Don't the "generic" MFM controllers have to record disc geometry somewhere? Maybe it's recording them in a spot on disc that clashes with the DR-DOS boot record?

I don’t know that much about boot record locations on MFM drives but DR-DOS was distributed as a 100% compatible OS so it should be the same as MS/PC-DOS.
As for the drive geometry, it’s either pulled from the controllers table or entered manually if dynamically low level formatted. For the Seagate ST225, that WD controller already had the drives parameters.