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From: Peter.Fitzsimmons@p1.f628.n250.z1.FIDONET.ORG (Peter Fitzsimmons)
Newsgroups: comp.os.os2
Subject: Re: OS/2 and Hard Drives
Message-ID: <491.25CC1FF0@weyr.FIDONET.ORG>
Date: 2 Feb 90 10:30:55 GMT
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 >  >If os/2 didn't use the BIOS, than how can you explain my 150mb drive
 >  >working when it is defined as type 1 in my CMOS (type 1 == 10mb I
 >  >think)?  My WD1007's BIOS knows the real size of my disk.
 > 
 > Because by the time POST completes and the operating system bootstrap is 
 > loaded, the INT 41H drive parameter vector is pointing at a "drive type" 
 > that the WD1007 has constructed during POST.

 Thanks, that makes sense.

But if the drive params are 'constructed', as you say, where IS the
vector pointing to?  Surely it can't be in RAM?

Hmmm, sudden realization:  The PS/2's with large ESDI disks have
slightly less than 640K free in lower memory.  If I remember
correctly,  this is where is stores the drive parameter table.
After reading your note, it all clicked in.  The ps/2 POST is
building the table there and then only reporting 639K free.

Do you know how the WD1007 does it?


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