SDI Disk Controllers

This document outlines the features and specifications of Digital's SDI (Standard Disk Interconnect) controller family, including the UDA50, KDA50, and KDB50 models. Designed to work within the Digital Storage Architecture (DSA), these intelligent, microprocessor-based controllers offload disk I/O tasks from the host CPU, significantly improving system throughput and performance. Key features include high-speed data handling, extensive error detection and correction (using 170-bit Reed-Solomon ECC), and advanced performance optimizations like seek ordering and rotational latency minimization. The controllers support radial connection to up to four RA-series drives, ensuring disk availability and eliminating daisy-chain interdependencies. Comprehensive specifications for each model are included, detailing power requirements, operational environment, and physical characteristics.