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