Disk Drives Over 1 Gigabyte; Extended Translation (Using Dos 5; The Dos One Gigabyte Limit; When To Use Extended Translation - Adaptec AHA-1740A Installation Manual

Appendix A
Disk Drives Over l Gigabyte
Extended Translation (Using DOS 5)
Adaptec host adapters have always supported the full range of
disk drive sizes under all major operating systems. As disk
drives have recently grown beyond 1 Gigabyte in formatted ca-
pacity, they have run up against the DOS 1024 cylinder limit.
To continue to provide support of all SCSI disk drive capacities
under DOS, Adaptec has introduced extended translation for
the AHA-1740A and AHA-1742A. This new feature bypasses
the DOS disk capacity limit and supports disk drives up to un-
der DOS, providing room for years of disk drive evolution.
The DOS One Gigabyte Limit
All versions of DOS are limited to 1024 cylinders of capacity
per drive. The standard translation scheme for SCSI host adapt-
ers, using 64 heads and 32 sectors, provides a maximum acces-
sible capacity of 1 Gigabyte.
To eliminate the 1 Gigabyte limit, Adaptec's new extended
translation feature uses 255 heads and 63 sectors, extending
the disk drive capacity limit under DOS to 8 Gigabytes.
When to Use Extended Translation
With DOS Version 5 Only
NetWare®386™ and the newer versions of UNIX® do not share
the 1024 cylinder limit of DOS and do not
re~ire
extended
translation to support large disk drives. OS/2 does not
currently support extended translation.
A-1