Adaptec AHA-2742 Installation Guide - Page 3

orientation is maintained throughout the bus. Pin 1 of the SCSI cable is designated by a colored stripe on one edge of the flat ribbon cable. Pin 1 of the host adapter or SCSI device connector is usually designated by a delta or arrow symbol (v) on the connector. The internal connectors for SCSI Channel A and SCSI Channel B (AHA-2740-T/2742-T only) use a 50-pin SCSI flat ribbon cable with a 50-pin header internal connector. External SCSI Cables The external connector for SCSI Channel A uses a 50-pin shielded cable with a high-density external connector. External cable connectors are keyed and can only be plugged in one way; Pin 1 orientation is automatic. Floppy Cables (AHA-2742/2742-T only) The floppy connector uses a 34-pin floppy ribbon cable with a 34-pin header connector. Make sure to maintain Pin 1 orientation as previously described in Internal SCSI Cables. Termination on the SCSI Bus The first and last physical SCSI devices on the ends of the SCSI bus must have a set of resistors called terminators either installed or enabled. All other SCSI devices installed between the ends of the SCSI bus must have their terminators either removed or disabled. Terminating the Host Adapter The factory installed bus terminators on the host adapter are enabled by default. Host adapter termination should be disabled if you attach SCSI devices to both internal and external connectors, since the host adapter would then be in the middle of the SCSI bus. Table 3 describes the three possible SCSI device and host adapter (AHA) configurations. Table 3. SCSI Device and AHA Configuration Devices Connected To Host Adapter Internal devices only (AHA at end of cable) External devices only (AHA at end of cable) Internal and External devices (AHA in between) AHA Termination On/Enabled On/Enabled Off/Disabled 4 Enabling or disabling host adapter termination is software selectable only. To disable termination on the host adapter, refer to Section 6 , Configuring the Host Adapter for instructions. Terminating Other SCSI Peripheral Devices Check the manufacturer's documentation to determine how to enable or disable SCSI bus termination on your SCSI peripheral device(s). SCSI ID Setting For each device located on the SCSI bus, a unique SCSI ID (0-7) must be reserved. The default value for your host adapter is SCSI ID 7. Refer to Section 6 , Configuring the Host Adapter for instructions on changing the SCSI ID for the host adapter. Refer to the SCSI device documentation for information on changing the SCSI ID on other SCSI devices. Reassemble the System Follow your system and SCSI device documentation to replace the system cover and connect all system and SCSI device power cables. 6 Configuring the Host Adapter A Configuration diskette containing an EISA Configuration utility is normally supplied by the EISA system vendor. Depending on the EISA Configuration utility supplied with your system, host adapter configuration will vary. The basic steps involved in running the EISA Configuration utility are explained in this section. Run the EISA Configuration Utility Place the bootable Configuration diskette in an operative drive and reset the system to boot from this diskette. Run the EISA Configuration utility as instructed by the EISA system vendor. Copying Files The Configuration utility typically allows you to select among a number of options, including copying new configuration files. Select this option to install the !adp7771.cfg and adp7770.ovl files from the host adapter diskette to the bootable Configuration diskette. If the Configuration utility does not 5 provide such an option, you can also use the DOS Copy command to copy these files to the bootable Configuration diskette. Select the Host Adapter Once the files have been copied, run the option in the Configuration utility that allows you to configure the EISA slot in which the host adapter is installed. A screen listing the host adapter parameters is displayed. Note If your host adapter is an AHA-2740-T/2742-T, a set of parameters for SCSI Channel B is displayed and can be configured. Configure the Host Adapter Parameters Select values for each setting as instructed on the screen's menu. Interrupt Level-selects the IRQ level of the host adapter. Bus Release Time-selects the EISA bus release time used when the host adapter gets preempted in bus master mode. Data FIFO Threshold-selects the data FIFO threshold percentage used by the host adapter. Host Adapter BIOS Address-selects the base BIOS address of the host adapter. Host Adapter SCSI ID-selects the SCSI ID (0-7) for the host adapter. SCSI IDs 0 and 1 should be reserved for SCSI hard disk drives. Each installed SCSI device must have a unique SCSI ID. SCSI Bus Parity-allows you to enable or disable SCSI bus parity on the host adapter. SCSI Selection Timeout-selects the SCSI selection timeout used by the host adapter during the SCSI selection phase. SCSI Bus Reset at Power-on-allows you to enable or disable a SCSI bus reset generated by the host adapter during its power-on initialization, and after a Hard Reset. 6