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Q99290: Adaptec/MS-DOS Support for Drives Greater than 1 GB

Article: Q99290
Product(s): Microsoft LAN Manager
Version(s): 
Operating System(s): 
Keyword(s): 
Last Modified: 30-JUL-2001

SUMMARY
=======

The Adaptec manual is somewhat misleading when it states that MS-DOS imposes a
1G limit on storage drives. MS-DOS is limited to 1024 cylinders, but it allows
more heads and sectors per track (255 heads and 63 sectors) than does Adaptec
(64 heads and 32 sectors). Adaptec adopted the SCSI standard in order to surpass
1G, but a drive is not going to run unless MS-DOS supports it.

To support drives greater than 1G, you need to enable extended BIOS translation
in EISA CONFIG, and Adaptec's 9/17/92 bid works only when the drive isn't the
boot device.

Problems can occur when it IS the boot device. When setting up a drive's
geometry, DISK.TSD determines if it is the boot drive. If it is, use the ROM
chain entry (BIOS related) to set the geometry because the machine has to boot
from the ROM. This is probably where the Adaptec problem arises: the bid is
reporting the correct values but the BIOS information has to come from the
adapter, which appears to be setting values incorrectly.

Additional query words:

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