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                          INTRO.DOC
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This file presents general information about the NCR SDMS software 
product. It is is divided into the following sections:

General Description
Overview
   SCSI BIOS
   SCSI Device Drivers
Before You Begin
   Basic Rules For SCSI Host Bus Adapter and Device Installation
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*********************** General Description ***********************

The NCR SCSI Device Management System (SDMS) is a complete software package 
that solves the increasingly complex problem of managing system I/O. It 
seamlessly addresses hardware and software interfaces by supporting the NCR 
family of PC SCSI processors and controllers, and a wide range of SCSI 
peripheral devices, while offering interoperability across application 
programs, operating systems, and host platforms. SDMS consists of a resident 
SCSI BIOS that manages all SCSI controller or processor specific functions, 
and a series of SCSI device drivers that provide operating system and 
peripheral specific support. 

SDMS provides a standard method to interface SCSI I/O subsystems with devices, 
operating systems, and application software. It also enhances system 
capabilities already provided by SCSI controllers and processors by 
facilitating multi-threaded I/O support, system-wide SCSI device access, and 
creation of new applications.



*************************** Overview ******************************

An NCR SCSI controller or processor can control peripherals such as hard disk 
drives, CD-ROM drives, tape drives, and removable media. SCSI peripherals are 
intelligent devices that do not need the constant attention required by 
non-intelligent devices. Up to seven SCSI peripheral devices can be connected 
(via the SCSI bus) to a SCSI host bus adapter card on which the SCSI 
controller or processor resides.

A SCSI host bus adapter can also function as a secondary adapter in a system 
which already has a primary hard drive controller card (IDE, ESDI, ST506). 
Only SCSI host bus adapters will do this, expanding the possibilities for 
system configuration. 


* SCSI BIOS *

A SCSI BIOS is the bootable ROM or non-bootable RAM based code that manages 
SCSI hardware resources. It is specific to an individual NCR SCSI controller 
or processor. An NCR SCSI BIOS integrates with most standard system BIOS, 
extending the standard disk service routine provided through INT13. It is also 
responsible for processing and executing SCSI requests communicated from a 
SCSI device driver or application. 

An important feature of the SCSI BIOS is that it is completely operating 
system independent. All ROM based SCSI BIOS support booting from a SCSI hard 
disk, and can be easily ported to a variety of hardware platforms. They also 
support 16- and 32-bit operating systems running under real or protected 
addressing modes.

The NCR SCSI BIOS provides a hardware independent interface which isolates the 
operating system drivers and SCSI application programs from the underlying 
hardware. This enables a single driver to work with any host adapter or SCSI 
controller which has an NCR SCSI BIOS.

During its boot time initialization, the SCSI BIOS determines if another hard 
disk is already installed. If there is, the SCSI BIOS will map any SCSI drives 
it finds behind the drive already installed. Otherwise, the SCSI BIOS will 
install drives starting with the system boot drive. In this case, the system 
will boot from a drive controlled by the SCSI BIOS. 
If the operating system used is DOS 5.0 or above, the SCSI BIOS allows access 
to a maximum of seven SCSI hard disks via INT13. DOS has the ability to 
control up to eight hard drives via INT13. The number controlled by the SCSI 
BIOS depends on the number of non-SDMS controlled disk drives in the system. 


* SCSI Device Drivers *

The SCSI device drivers translate an operating system I/O request into a data 
structure, and transport the structure to the SCSI BIOS. An NCR SCSI device 
driver is operating system specific, but completely hardware independent. The 
hardware specifics are addressed by the SCSI BIOS.

Although a driverless solution exists, and provides adequate support for many 
applications, loading a driver (or drivers in some cases) will provide 
additional features. Connecting peripherals other than hard disk drives, for 
example, requires loading the appropriate driver(s). The following chapters 
provide information on the use and installation of these drivers within each 
operating system.


* Concatenated SCSI Device Drivers *

NCR SDMS 3.0 also offers operating system specific drivers with a chip 
specific SCSI BIOS appended to the end. These are called concatenated SCSI 
Device Drivers and allow a ROMless solution when connectivity rather than 
bootability is the goal. If the Host Bus Adapter (HBA) does not have a 
resident ROM (is non-bootable), the system will boot from a non-SCSI device, 
or another bootable SCSI device, and will access the board and all connected 
peripherals through the concatenated driver(s). 



************************ Before You Begin *************************

SDMS software requires an IBM PC/AT or compatible computer with an 80386 or 
higher microprocessor. An understanding of basic operating system commands is 
assumed. In addition, users of this manual should have a general knowledge of 
the SCSI interface standard. For background information on this subject, 
refer to the SCSI-2 specification or the book SCSI: Understanding the Small 
Computer System Interface.

Before using the SDMS software, the NCR SCSI controller should be configured 
into your system, taking into account the configuration of other host bus 
adapters and system resources (see Basic Rules... listed below).

Note:   NCR recommends that all data be backed up before making any changes or 
installing any software, including NCR SCSI controllers and software. Failure 
to adhere to this accepted computer practice may lead to irretrievable loss of 
data.


* Basic Rules For SCSI Host Bus Adapter and Device Installation *

Both ends of the SCSI chain must be terminated. Refer to the hardware manuals 
for the devices and the host bus adapter to determine where and what the 
terminators are.

Each SCSI device must be configured with a different ID number. Refer to the 
hardware manuals for the devices and the host bus adapter to locate where the 
jumpers or dip switches are for setting ID numbers. Usually the host bus 
adapter is ID 7. The devices are then set at IDs 0 through 6. The bootable 
hard drive must have the lowest ID. 

The red or blue line on a standard SCSI cable (or the black line on one end 
of a multi-colored SCSI cable) designates pin one on the cable connector and 
must connect to pin one on the device or host bus adapter connector. Refer to 
the hardware manuals for the devices and the controller to locate pin one of 
the connector.

If the system already has an internal bootable hard drive (IDE, ESDI, ST506), 
the drivers for the SCSI device(s) must reside on the internal bootable hard 
drive.

SCSI hard drives are already low level formatted. The installer need only 
partition and format the drive.

Whenever installing multiple host bus adapters in one system, each card must 
be set to a different base BIOS address, as long as the primary adapter has a 
lower base BIOS address than the secondary adapter(s). 

