Specifications

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2.5.1 Normal Use of SCSI
The board's SCSI bus interface can serve a variety of purposes, including connection of hard disk
controllers, tape controllers, text scanners, and printer and communications servers. Support is
provided by the board's ROM-BIOS for booting of DOS from a SCSI device such as a hard disk.
Virtually any device compatible with the SCSI Common Command Set for direct access devices
can be used through the ROM-BIOS support. Some examples of direct access SCSI devices that
can be accessed as DOS drives are hard disk drives, magnetic bubble drives, high density floppy
drives, and some tape drives.
The Little Board/286 comes with a diskette containing software drivers and utilities for normal
DOS operation using hard disks and other SCSI direct access devices. Included are a formatter, a
partition editor, and a device driver capable of multiple drive and partition operation. Refer to
Chapter 4 for information on software setup and drive preparation.
PC-DOS version 3.x requires that drives larger than 32 megabytes be partitioned into more than
one "partition", while DR-DOS and PC-DOS 4.x allow a maximum partition size of 128M bytes.
If desired under PC-DOS 3.x, each physical drive can be have a maximum of up to four partitions,
32 megabytes or smaller, allowing the use of drives as large as 128 megabytes. PC-DOS 4.x and
DR-DOS limit drive size to 512M bytes (four 128M byte partitions).
There are several other types of SCSI devices besides direct access devices. SCSI's additional
device types include sequential access devices (e.g. tape), printer devices, read-only devices (e.g.
CD-ROM), and processor devices (e.g. CPU's). In general, these other device types require
special application programs, utilities, or driver software for use. For example, Ampro offers an
optional tape backup program which can be used for DOS environment hard disk backup.
Hard disk support for operating systems other than DOS may or may not be automatically
available through the board's ROM-BIOS resident hard disk driver. This depends on whether the
operating system in question uses BIOS calls exclusively for the hard disk function, and whether
the operating system has any special ROM-BIOS constraints (such as re-entrancy). Some
operating systems -- multitasking ones in particular such as Unix -- interface directly with the
hardware (e.g. attempt to directly program an AT compatible hard disk controller) and bypass
BIOS. In those situations, the operating system must be modified to add an appropriate SCSI
hard disk driver to use the to take advantage of the board's SCSI interface. An alternative is to use
the Ampro MiniModule/ATDisk controller board interface, which provides compatibility with
standard ATA-equipped hard disk drives. Refer to the Ampro MiniModule/ATDisk Technical
Manual for additional information regarding the board's capabilities.
2.5.2 The Ampro SCSI/BIOS
Through the universal bus interface and command protocols offered by SCSI, it has become
possible to connect a wide variety of mass storage devices to a computer system with virtually no
changes to system software. To this, Ampro has added a further layer of universality: the
SCSI/BIOS.