Specifications

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3.7 USING SCSI HARD DISK DRIVES
One unique feature of the Little Board/286 is that its ROM-BIOS contains hard disk support
functions, which map to the board's Small Computer System Interface, rather than to a standard
AT bus hard disk controller. This has the advantage of offering the added flexibility of SCSI
device support, with its benefits of interchangeability of peripherals, flexibility of configuration,
and ease of system upgrading and support.
Hard disk devices accessed via the board's SCSI interface are available to DOS through standard
ROM-BIOS functions (INT 13), supplied by the Ampro SCSI/BIOS contained within the board's
ROM-BIOS. The ROM-BIOS hard disk support allows direct system booting from SCSI
Common Command Set direct access devices. In addition to hard disks, other types of SCSI
direct access devices can be used interchangeably to provide a fully compatible hard disk function.
These include bubble memory drives, RAM disks, optical disks, and tape drives.
Virtually all DOS applications run normally in this SCSI-based hard disk environment, because
programs nearly always use either DOS or ROM-BIOS functions for disk drive access. It is
extremely rare for DOS environment software to attempt to access hard disk controller hardware
directly. If a program does require disk controller hardware access, it will need to be modified to
use the board's SCSI hardware or SCSI/BIOS functions. In this case, low level SCSI functions
available within the board's ROM-BIOS can be used to simplify the task.
In most cases, SCSI hard disk drives can be used without the need for custom programming. The
board's ROM-BIOS and SCSI support software allow the use of one or more hard disk drives
under PC-DOS, MS-DOS, DR-DOS.
A combination of Ampro and DOS utilities are used in the formatting and preparation of SCSI
hard disk drives. Included on the Ampro utilities diskette are utilities for SCSI drive formatting,
parking, and other SCSI functions.
3.7.1 Drive Parameter Setup
Several parameters need to be set in the board's Configuration Memory, using the Ampro SETUP
utility. These are outlined below. For detailed instructions on SETUP, refer to the program's
description in the Appendix of this manual.
n SCSI Initiator ID -- the Ampro Little Board/286 is the SCSI Initiator in its transactions
with SCSI Target devices such as hard disk drives. Every SCSI device (Target or Initiator)
must have a unique ID, between 0 and 7. Usually, the Ampro Little Board/286 is set for "7",
because this is the highest priority ID, and because the Ampro SCSI/BIOS performs a SCSI
bus Reset function on system powerup or reset when the CPU board's ID is 7.
n SCSI Target Device ID's and LUN's -- the Configuration Memory has space for the
specification of one or more SCSI target device ID's and Logical Unit Numbers (LUN's).
Every SCSI Target device must have a SCSI ID, between 0 and 7, normally set by jumpers
or switches on the device. Unless multiple devices are operated from a single SCSI Target
controller, the LUN will be 0. For example, a typical system with a SCSI drive connected to
it will have the drive configured as ID0, LUN0. Multiple SCSI drives, if present and
properly formatted, can result in multiple DOS hard disk drives being installed by the ROM-
BIOS at system boot time.