hard-sector 5 1/4 disk

From: Richard Erlacher <edick_at_idcomm.com>
Date: Tue Oct 30 21:18:14 2001

you said " ...
>
> No, it is not conceivable, since there is no light and photocell to EVER
> EVER see the index pulse.
>
..."
I have to disagree, actually, because the Apple diskettes all seem to have the
holes, not that it matters. While the drive may not have the means to "see"
them, since it's about ignoring them, the inability to see them makes them
easier to ignore, which, in turn, explains why someone might happily use hard
sectored diskettes in an Apple][. That was the point about which there seems to
have been some confusion.

and " ...
Except that they did too much in firmware, . . .
..."
Which, admittedly, I don't understand, since the PROM they used was rather
small. (...that's where the firmware lives, doncha know...) Most of the work
was in the software, actually, since it had to do what the disk format required,
and figure out along the way which one it was.

I've never liked Apple-disk-related problems, since the Apple system was
incredibly fragile and highly unreliable. The first Apple client I had who had
been using an Apple][+ in his business summarily took his ][+, drives, and
monitor, the whole shebang, out to his dumpster the day I moved his database to
a CP/M system with a conventional FDC and a conventional pair of 8" DSDD drives.
I'd say he was in hog heaven. His business picked up (though I don't know that
the switch had anything to do with that) and his monthly expenditure for MAALOX,
Whiskey, and prune juice was substantially reduced. Moreover, he got to see a
lot more of his wife and kids.

Until a few weeks back when I got into retrieving old 6502 source files, I had
forgotten what a piece of crap that disk subsystem was. No wondern so many
folks switched to 8" drives. I surely wish I could find an old SVA controller
... <sigh> It's a real wonder microcomputers caught on as well as they did,
given the standard set by the Apple ][. The work WOZ did to create the disk
subsystem was really ingenious, but still orders of magnitude less reliable than
what was offered on more conventional systems.

Dick

----- Original Message -----
From: "Fred Cisin (XenoSoft)" <cisin_at_xenosoft.com>
To: <classiccmp_at_classiccmp.org>
Sent: Tuesday, October 30, 2001 7:16 PM
Subject: Re: hard-sector 5 1/4 disk


> On Tue, 30 Oct 2001, Richard Erlacher wrote:
> > It's conceivable that the software that the Apple][ used didn't look for an
> > index pulse until, nominally, the "right" time, at which point it waited for
it,
> > then proceeded, in which case the extra holes in the index track (not a
magnetic
> > track) would have no impact.
>
> No, it is not conceivable, since there is no light and photocell to EVER
> EVER see the index pulse.
>
> > The format was, nevertheless, soft-sectored, thereby allowing a smooth
> > transition from 13 sectors to 16 sectors, without a major redesign.
>
> Except that they did too much in firmware, . . .
>
>
Received on Tue Oct 30 2001 - 21:18:14 GMT