*************************************************************************** INTRO.TXT *************************************************************************** This file presents general information about the Symbios Logic SDMS software product. It 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 ************************************************************************** *************************** General Description ************************** The Symbios Logic 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 Symbios Logic family of 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 Symbios Logic 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 15 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 code that manages SCSI hardware resources. It is specific to a family of Symbios Logic SCSI controllers or processors. An Symbios Logic SCSI BIOS integrates with a 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 ported to a variety of hardware platforms. They also support 16- and 32-bit operating systems running under real or protected addressing modes. The Symbios Logic 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 Symbios Logic 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 eight SCSI hard disks via INT13. The number controlled by the SCSI BIOS depends on the number of non-SDMS controlled disk drives in the system. For more information on SCSI BIOS control of hard disk drives, see Chapter 2, Device Drivers for DOS/Windows. * 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 (see figure 1-2). An Symbios Logic 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 for the DOS operating system, 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. **************************** 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 standard. For background information on this subject, refer to the SCSI-2 specification or the book SCSI: Understanding the Small Computer System Interface. Sources for these publications are listed in the preface of this document. Before using the SDMS software, the Symbios Logic 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). Symbios Logic recommends that all data be backed up before making any changes or installing any software, including Symbios Logic SCSI controllers and software. Failure to adhere to this accepted computer practice may lead to loss of data. * Basic Rules For SCSI Host Bus Adapter and Device Installation * Both ends of the SCSI bus must be terminated. Refer to the hardware manuals for the devices and the host bus adapter to determine what the terminators are, and where they are located. 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 (plus 8 through 15 for wide SCSI). The bootable hard drive must have the lowest numerical 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. For non-PCI devices, 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). Also, make certain each adapter is set to a different base I/O address and IRQ.