User`s manual

Introduction

1-4

Single Board Computers SCSI Software UserÕs Manual

The following publications are available from the sources indicated.

ANSI Small Computer System Interface-2 (SCSI-2), Draft Document X3.131-

198X, Revision 10c; Global Engineering Documents, P.O. Box 19539, Irvine,

CA 92714.

NCR 53C710 SCSI I/O Processor Data Manual, document #NCR53C710DM;

NCR Corporation, Microelectronics Products Division, Colorado Springs, CO.

NCR 53C710 SCSI I/O Processor ProgrammerÕs Guide, document

#NCR53C710PG; NCR Corporation, Microelectronics Products Division,

Colorado Springs, CO.

Deﬁnition of SCSI

According to the SCSI-2 specification,

"SCSI is a local I/O bus that can be operated over a wide range of data rates.

The primary objective of the interface is to provide host computers with device

independence within a class of devices. Thus, different disk drives, tape

drives, printers, optical media drives, and other devices can be added to the

host computers without requiring modifications to generic system hardware

or software. Provision is made for the addition of special features and

functions through the use of vendor unique fields and codes. Reserved fields

and codes are provided for future standardization."

General Description of the SCSI Software

The SCSI Software, or Firmware, for the Single Board Computers (SBCs)

provides comprehensive access to the SCSI bus. It consists of Motorola

Processor (MPU) code and NCR SCSI SCRIPTS code (SCRIPTS) used to

control the NCR 53C710 SCSI I/O Processor (SIOP). The SIOP provides the

actual physical connection to the SCSI bus.

The SCRIPTS are instructions executed by the SIOP which control the specific

operations and functionality of the SIOP. The MPU code formats command

control information in a manner compatible to the SCRIPTS. It also handles

situations where the SIOP or SCRIPTS cannot perform the required function.

From an application viewpoint, the SCSI Software can be interconnected with

the application in order to provide access to the SCSI bus. SIOP programming

is not required in order to create the interconnection. The SCSI Software

allows access to the SCSI bus in conformance with SCSI bus protocols and can

be linked into the final application to create the connection to the SCSI bus.

Typically, an application specific device driver is used to interface application

code with the SCSI Software.