There is a software device made in Russia (PC-3000) for repairing hard
drives. It comes with a PCI card that allows the user to gain control
over the hard drive independently of the OS.

The PCI card is just a SATA controller with special driver, nothing else. Such software works by sending vendor-specific ATA commands to the hard drive, and MS's ATA stack is poor in supporting them, thus the special driver.

the drive. I can read OK, but it fails in write mode ...even in
simulation mode.

Strange. Maybe a bug in SiL's drivers.

reset the transfer speed. I remember the old days with IRQ conflicts

Any modern PCI hardware is free from this issue.

Si3112.sys
SiRemFil.sys (filter)
SiWinAcc.sys (accelerator)
SilSupp.cpl (property sheet in the Control Panel)

On my machine with SiL, I only had Si3112.sys which was linked to MS's SCSIPORT.SYS. Nothing else.

I'm confused about the SCSI aspect. What has it to do with a SATA
controller that uses an ATA/ATAPI standard?

Because the driver plugs in to the SCSI stack of the OS. Nothing surprising. For instance, in NT4, the standard PC/AT ATA driver was plugging to the SCSI stack.

imapi.sys

Pre-Vista MS's burning toolkit. Good software like Nero does not use it.

redbook.sys

Audio.

SiRemFil.sys (filter again)

I have no such filter.

It seems to use imapi.sys.

Yes.

memory between 640K and 1 meg just as the Si3112 does.

Are you sure that the modern PCI device will have such hardcoded memory region? PCI devices use configurable memory apertures.

Can you connect the SATA DVD to the usual south bridge controller? will there be any speed difference?

--
Maxim S. Shatskih
Windows DDK MVP

http://www.storagecraft.com