Digital StorageWorks Fiber-Optic UltraSCSI Extender (DWZGA) User's Guide

This User's Guide describes the Digital Equipment Corporation StorageWorks Fiber-Optic UltraSCSI Extender (DWZGA), a system designed to extend a single Ultra wide differential SCSI bus up to 15 kilometers using a fiber-optic link.

Key aspects of the DWZGA include:

• Two-Unit System: It operates with two DWZGA units connected back-to-back: a LOCAL unit at the host end and a REMOTE unit at the device end.
• Intelligent Extension: Rather than simple signal conversion, each DWZGA unit functions as an intelligent SCSI controller, performing local SCSI transactions. This approach preserves SCSI timing requirements, making the extender transparent to the host and devices and allowing features like arbitration and disconnect/reconnect over long distances.
• Data Integrity: The system ensures data validity through features like byte-level echo checking, vertical parity, 8B/10B encoding, and transfer count comparison.
• SCSI Support: It supports both wide (16-bit) and narrow (8-bit) SCSI buses, as well as synchronous (up to 20 MB/sec) and asynchronous data transfers. SCSI commands are extended unidirectionally from host to peripherals.
• Optical Data Link (ODL): Utilizes a LASER-based 1300nm singlemode fiber with Duplex SC connectors.
• User Operations: The guide provides comprehensive instructions for installation (unpacking, cabling the LOCAL and REMOTE units), configuration (setting front panel DIP switches for SCSI features and target addresses), maintenance (cleaning fiber-optic cable connectors and ports), and troubleshooting common issues using LED indicators.

The document emphasizes the importance of proper switch settings for optimal performance and provides detailed descriptions of the front and rear panel components.