According to Manuel Bouyer:
>
>If someone knows how it works - I suppose the alternate register status
>doesn't exist on ST506 drives/controller (it has the property
>to not ack the interrupt on IDE systems, where the status register does) ?
>

You suppose correctly - quite a few years back the wd driver was
broken for my ESDI drives, due to the lack of the alternate status
register.  This register seems only to be available on "modern" (such
a relative term) IDE drives/controllers.

I found the register layout for the drives in a book called "PC
Hardware Handbook" or something like that - a big, fat compendium of
all sorts of data on PC hardware.  If you are interested I can get you
an ISBN.

-- 
Brett Lymn, Computer Systems Administrator, British Aerospace Australia
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