Nicolet 660

Mr Ian Primus ian_primus at
Wed Feb 11 12:16:32 CST 2009

--- On Wed, 2/11/09, John Floren <slawmaster at> wrote:
> The disk has either 8" or 9" platters; the
> original drive (which was
> replaced year back) was a Priam so the new one may be the
> same or it
> might possibly be a CDC.
> It's not totally clear whether the problem is in the
> drive or the
> controller. The drive spins up, but the disk diagnostic
> test fails.

The disk diagnostic on the computer, or on the drive? The newer CDC Sabre drives have built-in diagnostics. If you pop the center panel off the front, it reveals a hex keypad and an LCD display. Older CDC drives will have an LED hex display and a couple buttons. (Of course, not all of them have this, it was an option...).

Does the disk come ready, or does the fault light come on after it spins up? Can you bring the disk online, and hear the heads load?

If you find out what model drive it is, you can get the manual (Bitsavers has a fair number of CDC manuals), and find the diagnostic commands for it. You should be able to unhook the drive from the computer, and power just the drive, and run tests right on the disk. If it seeks OK and spins, then you might have a bad interface board on the drive, or on the computer, a bad cable, improper termination (ensure the terminator's ground lead is connected!), or maybe just a corrupt filesystem, or possibly still bad blocks/tracks/surfaces on the disk. I don't remember if there are any on-disk read/write tests or not, but you wouldn't want to corrupt the system software anyway.

Can you boot the computer off floppy disk/tape/whatever?


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