RP04 Device Control Logic User's Manual

This document is a user's manual for the Digital Equipment Corporation (DEC) RP04 Disk Drive's Device Control Logic (DCL), published in November 1976.

The manual describes the DCL as one of the two major functional parts of the RP04 Disk Drive, with the other being the DEC 773 Disk Storage Drive. The DCL is responsible for interpreting and executing commands, managing data transfers, and allowing access by two different controllers.

Key aspects covered include:

• Functionality:

  • Dual Controller Operation: The DCL supports simultaneous access by two different controllers (e.g., for PDP-11, PDP-15, and DECsystem-10 systems) on a first-come, first-serve basis.
  • Read/Write Data Transfers: It handles synchronous data transfers for writing data (including disk pack formatting with header information) and reading data/headers from the disk.
  • Disk Addressing: It implements commands like "seek" to position read/write heads and "search" to optimize disk revolution time.
  • Interface Registers: The DCL exposes 16 interface registers to the controller for various functions including control, status, maintenance, error information, and disk addressing data.
  • Error Correction Capability: A notable feature is its built-in error correction logic, which detects errors during read operations and provides information (burst pattern and position) to allow software to correct the data.

• Physical Description: The DCL is a separate assembly attached to the RP04 Drive, housing various control logic printed circuit boards (PCBs), interface PCBs (for MASSBUS and MDLI), a power supply, and a power monitor.

• Specifications: It supports data formats of 20 sectors per track (256 18-bit words) or 22 sectors per track (256 16-bit words), features comprehensive error handling, and supports single or multisector data transfers.

In essence, the manual details the operational logic, physical components, and technical specifications of the DCL, which serves as the intelligent interface between computer systems and the RP04 disk storage mechanics.