IDE HD > 512 MB ??

IDE HD > 512 MB ??

Post by Dan Grays » Mon, 04 Dec 1995 04:00:00



I just bought a 1280 MB Western Digital Hard drive, and the manual says
that since MSDOS/Windows can't handle more than 512 MB, one should
lie to the CMOS ROM monitor, and tell it that your drive has only 1024
cylinders.  This seems like a rather dubious solution.

What is the recommended way to respond to this instruction?  I would like to
have an MSDOS/Windows partition and a linux partition on the drive.  I
don't want to futz with MSDOS software more than necessary, and in particular,
it would be nice to avoid upgrading my BIOS ROM, and to avoid using the
"Ontrack Disk Manager", which is supposed to get around the problem
somehow.  (Does anyone --understand-- this?)  I don't mind limiting
msdos to < 512 MB on this drive.

 
 
 

IDE HD > 512 MB ??

Post by Patrick Yane » Tue, 05 Dec 1995 04:00:00



>I just bought a 1280 MB Western Digital Hard drive, and the manual says
>that since MSDOS/Windows can't handle more than 512 MB, one should
>lie to the CMOS ROM monitor, and tell it that your drive has only 1024
>cylinders.  This seems like a rather dubious solution.

The result would be that you're 1280M hard drive would magically
transform into a 512M one (assuming all other params are entered as they
should).

Quote:>What is the recommended way to respond to this instruction?  I would like to
>have an MSDOS/Windows partition and a linux partition on the drive.  I
>don't want to futz with MSDOS software more than necessary, and in particular,
>it would be nice to avoid upgrading my BIOS ROM, and to avoid using the
>"Ontrack Disk Manager", which is supposed to get around the problem
>somehow.  (Does anyone --understand-- this?)  I don't mind limiting
>msdos to < 512 MB on this drive.

You don't think they'd have made the HD if it wasn't going to be
recognized, do you?  It'll probably use the "virtual head" deal to get
around the cyl limit.

I have no idea how or why it works, but my BIOS reports my 1080M HD as
having 64 heads, when it really has only 16.  Somehow, this brings the
cylinder count down around 600-something.  Maybe some more experienced
computer user out there is capable of explaining why, but it somehow will
work.

 
 
 

IDE HD > 512 MB ??

Post by Peter Herweij » Fri, 08 Dec 1995 04:00:00


 >You don't think they'd have made the HD if it wasn't going to be
 >recognized, do you?  It'll probably use the "virtual head" deal to get
 >around the cyl limit.

There's no problem at all in recognizing IDE (yes, plain old IDE if need
be) drives of up to 128 gigabyte.

There is a problem, however, of squeezing such a drive into the ordinary
BIOS calls. This is where the "virtual head deal" comes in; it's a bit
of magic performed by the BIOS. The drive has nothing to do with it.
Also, it's only a temporary fix that will work for drives up to 8GB, no
more.

 >I have no idea how or why it works, but my BIOS reports my 1080M HD as
 >having 64 heads, when it really has only 16.  Somehow, this brings the
 >cylinder count down around 600-something.  Maybe some more experienced
 >computer user out there is capable of explaining why, but it somehow will
 >work.

This is not a Linux specific question, so it's probably not a problem
pointing to a non Linux specific FAQ here:

For more details, take a look at the "Yet Another" Enhanced IDE/
Fast-ATA/ATA-2 FAQ posted on comp.sys.ibm.pc.hardware.storage, .misc and
comp.answers. It is also available, together with related material, by
FTP from

   ftp.netcom.com:/pub/cl/clau/ide_ata/
   ftp.rahul.net:/pub/lps/hard-disk/
   ftp.wi.leidenuniv.nl:/pub/faqs/
   rtfm.mit.edu:/pub/usenet/news.answers/pc-hardware-faq/enhanced-IDE/

and by WWW from:

   http://www.wi.leidenuniv.nl/ata/atafq.html
   http://www.seagate.com/techsuppt/faq/faqlist.html

Alternatively, you can get it through e-mail by sending me

message body is ignored. Replace "text" by "PostScript" or "html" if you
want those formats.

 - Peter

 
 
 

IDE HD > 512 MB ??

Post by Andrew Miles » Tue, 12 Dec 1995 04:00:00



>  >I have no idea how or why it works, but my BIOS reports my 1080M HD as
>  >having 64 heads, when it really has only 16.

I'd be surprised if it had 16 'cause that means 8 platters!

More like 4 heads on 2 platters...and then one head only does servo info,
which leaves 3 heads for data.

Anything over 5 platters (10 heads) is phony.

-- Andrew E. Mileski --

-------------------------------------------------------
Dark Matter Technologies Inc. - Ottawa Ontario, Canada!

 
 
 

1. HD > 512 MB for my old notebook?

Hi all,

I have an somewhat old Mitac 4022 notebook, a 486 DX2-66, ISA (I
guess), whose hard disk (Maxtor, approx. 250 MB) is broken. I want to
replace it with a new one with size ranging from 640 MB to 1 GB,
depending on the price.

The BIOS has an "USER TYPE" HD entry, but I decided to contact the
tech support before buying a new hard disk anyway.

The guy I talked to said that I could install any hard disk that fits
in the case (i.e. a 2.5" hd), but its size can be no more than 512 MB,
unless the HD comes with a "boot manager". He was not able to explain
in a satisfactory way (IMHO) the reason for this limitation.

Now, I was already aware of this limitation for pseudo-OSes (you know
what I'm talking about, uh?), but the guy spoke of it as a hardware
limitation. But again, he was not clear enough. The notebook runs only
Linux.

So, I'm asking here for your opinions about this problem.

Thank you in advance for your comments.

--

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