adaptec AHA-1540B/1542B Addendum to the User's Manual and Installation Guide Using Disk Drives Over 1 Gigabyte Under DOS 5 Extended Translation 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 capacity, 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. This new feature bypasses the DOS disk capacity limit and supports disk drives up to 8 Gigabytes in size under 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 adapters, using 64 heads and 32 sectors, provides a maximum accessible 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 (such as ATT/USL all versions, SCO v3.2.4 or later, ISC v3.0 or later) do not share the 1024 cylinder limit of DOS and do not require extended translation to support large disk drives. 0S/2 does not currently support extended PtPHPranslation, but IBM OS/2 v2.0 has support for full capacity with drives greater than one Gigabyte using HPFS partitions (exception: the boot partition is limited to one Gigabyte or less). NetWare 386 has full support for drives greater than a gigabyte with the standard translation scheme. With Disks Supported by the Host Adapter BIOS Only In a system that has only SCSI disk drives, the host adapter BIOS controls only those drives at SCSI IDs 0 and 1. For systems that have a mix of SCSI and non- SCSI disk drives, see the section titled Questions and Answers about extended translation in this addendum. Drives With Mixed Partitions Do not use extended translation on drives formatted with two or more partitions for different operating systems. Use standard translation. The sum of the DOS partitions will be less than 1 Gigabyte. Partitions for UNIX and NetWare can be larger than 1 Gigabyte when using standard translation. How to Use Extended Translation Back Up All Data Changing translation schemes ,on a disk drive erases all data on the drive Back up all drives on the SCSI bus prior to making the change, CAUTION If you have already partitioned a large disk drive with one translation method, conversion to another method will erase your data. Be sure to back up your disk drive prior to any change in the transla- tion method used. Install Jumper on J6 Install a jumper on pin pair 2 on jumper block J6. Refer to Figure 2-1 on page 2-2 of the User's Manual or Default Settings and Reference Diagram in the Installation Guide for the location of jumper block J6. Refer to the figure of jumper block J6 on page 2-9 of the User's Manual or the Installation Guide for the location of pin pair 2 (Spare 1). Installation of this jumper enables extended translation for disk drives controlled by the BIOS exceeding 1 Gigabyte in capacity. Other disk drives are not eligible for extended translation and will continue to use standard translation. Using fdisk To install a new disk, or to re-partition an existing disk, use the fdisk DOS utility as you normally would. The cylinder size increases to 8 MBytes when you enable extended translation. The size of the partition you request must therefore be a multiple of 8 MBytes. If you request a partition size that is not a multiple of 8 MBytes, fdisk will round up to the nearest whole multiple of 8 MBytes. Load ASW-1410 v3.0a Load ASW-1410 v3.0a for ASPI support of more than two disk drives or for non-disk peripheral devices. ASW-1410 is also often used for compatibility with 386 memory managers. You can upgrade for free to ASPI4DOS.SYS v3.0a by using the UPGRADE program on the Adaptec BBS. To protect your data, extended translation is not downward compatible with earlier versions of software drivers. If you intend to use ASPI-compatible software with your host adapter for support of more than two disk drives or for non-disk devices, install ASW-1410 v3.0a (or later). Questions and Answers About Extended Translation What Happens if I enable extended translation with SCSI drives that have less than 1 Gigabyte in capacity? Drives handled by the BIOS will use extended translation provided they are over 1 Gigabyte in formatted capacity. Drives with less than 1 Gigabyte of formatted capacity will use standard translation regardless of whether extended translation is enabled. Drives handled by the disk driver ASPIDISK.SYS will continue to use standard translation and not be capable of DOS partitions over 1 Gigabyte. How do I know which hard disk drives the BIOS controls? Your system allows up to two hard disk drives under BIOS control; first SCSI ID O, then SCSI ID 1. Your system may have either two non-SCSI, one non-SCSI and one SCSI, or two SCSI hard disk drives. What if I use older versions of software drivers with extended translation enabled? To protect your data, the host adapter will lock out out driver that does not identify itself as capable of extended translation. If you need to use software that is not compatible with extended translation, do not enable extended translation. Adaptec's ASW-1410 v3.0a (and later) is the appropriate ASPI manager software to use with extended translation enabled.