8" drive on PC troubleshooting

Vintage Computer Festival vcf at siconic.com
Tue Mar 1 17:18:34 CST 2005

On Tue, 1 Mar 2005, Tom Jennings wrote:

> On Tue, 1 Mar 2005, Vintage Computer Festival wrote:
> >> Wrong step rate! Poke a new on eint othe chip, or does it use the old
> >> table of junk INT 13h used to supoprt?
> >
> > Um, I'm not sure.  I'm not sure I understand the question either.  This is
> > a standard ISA IDE+floppy controller.  Should I try an older one?  Or hook
> > this up to an oldr PC from the 1980s?
> Different floppy drives have different specs for the stepper motor
> step rate. Big drives are often slower (eg. 8" but that's not
> always true).  With 5.25's you never think about it, but it used
> to be a Big Deal.
> If you step it too fast it shudders and goes nowhere. There's an optimum
> rate for performance, but "too slow" would be just fine for sucking data
> off diskettes one time.

So what I'm wondering is why it works fine when it's stepping towards the
center of the disk but not when it's stepping back out.

As I mentioned previously, the format command actually works: it steps 77
tracks inward, but can't move back to track 0 to write the boot sector and


Sellam Ismail                                        Vintage Computer Festival
International Man of Intrigue and Danger                http://www.vintage.org

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