patrmich wrote on 2024-03-18, 19:52:

Would you know a way to access the contents of a D5146H NEC hard drive (either on this computer or in another one) ?

This computer lost its CMOS settings due to the battery going flat (or dead), so the HDD geometry is also lost. You can set that up again but it looks like you need a special program on a bootable floppy to change the settings (these would persist as long as the power is applied).

It might be easier to try and transplant this HDD to a working machine, old enough that it doesn't have built-in IDE controllers (or those can be fully disabled). The HDD _must_ be paired with this particular controller, period. A different one but the same brand a model might work, but might also not. A different controller will not work. The easiest way is to transplant the HDD+controller to some 386 or early 486 mobo, add SCSI HDD controller to that and boot from SCSI or floppy, then use the SCSI free space to copy the files (or do a raw sector by sector read, that's preffered). Then transfer the SCSI HDD to a modern machine which can copy the file to network, or just add an Ethernet card to that 386 and use MTCP.

Use D5146H sector/head/cylinder count of 17/8/615 to set it up in the new machine. Predefined settings are fine, higher cylinder count is also fine as long as you are not planning on re-partitioning the drive (but don't run any HDD diagnostic tools like NDD, or it might "repair" something). Note, 17 sectors is assuming the drive is paired with a standard MFM controller. For RLL you should try 26 (again assuming the controller doesn't have it's own BIOS extension and won't patch it by itself).

EDIT: Forgot to add that D5146H probably doesn't auto-park. D5126 sure doesn't. So since you powered the machine the HDD has moved the heads to track 0 now. Treat it like an egg because if you mess up the heads will end up damaging track 0 (or themselves as well).