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AHA-1510A/20A Series User’s Guide
Stock Number: 510400-00, Rev. C Page: A-1
Print Spec Number: 491842-00
Current Date: 11/18/94 ECN Date: 11/29/94
A-1
ASupport for Large
Disk Drives
Extended Translation (Using MS-DOS 5.0)
All current versions of DOS are limited to 1024 cylinders per drive.
The standard translation scheme for SCSI host adapters, using
64 heads and 32 sectors, provides a maximum accessible capaci ty of
1 GByt e. As disk drives have recently grow n beyo nd 1 GByt e in for-
matted capacity, they have run up against the DO S 1024-cylinder
limit. To continue its support for all SCSI disk drive capacit ies under
DOS, Adaptec has included an extended translation scheme for
AHA-1520A/1522A host adapters. This feature supports disk drives
as large as 8GBytes under DOS.
When to Enable Extended Translation
Extended translation is disabled by default. Use extended transla-
tion for > 1 GByte hard dis k s und e r DOS . Use standard translation,
not extended translation, on drives formatted with two or more par-
titions for different operating systems. Par titions for NetWare can be
larger than 1 GByte when using standard trans lation. For instruc-
tions on enabling extended translation, see Chapter 2, Host Adapter
Configuration.
Caution: Be sure to back up your disk drive before you
change the translation method on a disk drive. All dat a
is erased when you change from on e translation scheme
to another.