[rescue] Durango Poppy II

Jeffrey Nonken jeff_work at nonken.net
Fri May 23 19:38:50 CDT 2003

On Fri, 23 May 2003 19:33:11 -0400, "Michael Free"
<mfree80286 at adelphia.net> wrote:

> AT machines typically were the first to have CMOS batteries... if yours are
> dead, the machine may have defaulted to no HDD and a 360K 5.25" drive in
> DSDD 96tpi drives are not compatible with current drives, if that's the
> 5.25" drive I'm thinking of. It was also used in the Tandy 2000 model...
> regular DSDD 5.25" disks are 48tpi. Somewhere out there, there may be a
> to run a 1.2 meg DSHD to read/write these disks.

Oooh, I wasn't thinking of the old Quad Density drives.

You can probably get away with formatting and using DSDD 48TPI disks in a
DSDD 96TPI drive. The only difference is the track width and stepping
distance; the encoding, flux density, and angular bit density are the same.
In other words, so-called Quad Density disks are just Double-Density disks
with twice as many tracks. OK, I'm talking in circles now...

I wouldn't DEPEND on QD-written DD disks, but you can probably use them in
a pinch. And chances are they'll be fine.

I sent one (and possibly two) Quad Density drives to Koyote along with the
TRS-80 model I. It's mostly an issue of identifying them (because I also
sent him at least one double-density drive that otherwise is identical, so
visual inspection won't be enough to distinguish them). If you need a
spare, you might be able to convince him to give it (them) up.

It might be possible to get an HD drive to act as a QD. The HD drive has a
DD mode; the software must then double-step the heads to switch tracks for
a DSDD disk. The rotational speed must also be changed. If I remember
correctly, any necessary modes can be controlled at the connector. However,
in PCs I think the HD drives run DD disks at 360 RPM; to accomplish the 300
RPM speed of DD disks they simply clock the data faster than they do for DD

Anyway, I recall the HD being able to do QD with the correct signals, but I
reserve the right to be wrong about that. And everything else. I do seem to
be good at it.

He can be outwitted by a jar of marshmallow fluff.

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