TOPS-20 MSCP Server

This document outlines the architecture, algorithms, and data structures of the TOPS-20 MSCP server. It functions as an intelligent disk controller interface for the TOPS-20 operating system, enabling communication with MSCP drivers via Systems Communications Architecture (SCA). The guide details:

• Connection Management: How SCA connections are established, monitored, and terminated.
• Command Processing: The state machine and queuing mechanisms for handling MSCP commands.
• Data Structures: Descriptions of the Server Connection Data Block (SCDB), command headers, and IORBs.
• Interface Definitions: Interaction details with the PHYSIO module for I/O operations and the user interface for disk selection via SMON/TMON/SETSPD.
• Error Handling: Timeout mechanisms and failure recovery procedures.