Defining Disk Image Dump Standard

From: Richard Erlacher <richard_at_idcomm.com>
Date: Tue May 30 18:40:57 2000

My data sheet makes it clear that the device uses both FM and MFM, but only
supports up to 250Kbps rates. it says, "With the exception of the Enable
Precomp/Ready line, the WD1773 is identical to the WD1770 Controller." It
also says "Single (FM) and Double (MFM) density."

The fact that Western left off the MO (motor-on) pin in favor of that enable
Precomp/ready seems to suggest that the device just might be capable of
handling 8" drives. I wonder if it can handle the clocks appropriately.
I've never seen one of these puppies. It would be interesting to know how
one is expected to use the precomp enable (/TG43 on a 179x) for anything
useful if the data is internally generated. That may explain why I've never
seen one. The offer a READY input on that same pin, for use on step and
read operations. I don't know how one is supposed to steer those two
signals since the associated signals are internally used from the same pin.

It's a good thing that sheet says "PRELIMINARY" at the top. I've checked to
make certain I haven't got a sample or two stashed away somewhere.

Dick
----- Original Message -----
From: allisonp <allisonp_at_world.std.com>
To: <classiccmp_at_classiccmp.org>
Sent: Tuesday, May 30, 2000 3:57 PM
Subject: Re: Defining Disk Image Dump Standard


> >> Just as an aside, I recently encountered a datasheet for the WD 1773
FDC
> >> (similar to 1770/72). Do you know of any systems in which it was used?
>
>
> No, they are not the same. the latter will do DD and the 1773 was single
> density.
> The 1773 was used on TRS80, Icom, and other early systems that were
> softsector.
>
> Allison
>
>
Received on Tue May 30 2000 - 18:40:57 BST

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