Discfile Control Type 270 Instruction Manual

This document serves as a comprehensive instruction and reference manual for the Digital Equipment Corporation (DEC) Discfile Control 270, a key component in a fast, random-access mass storage system designed for PDP-6 computers, used in conjunction with the Discfile 5022.

The manual begins by outlining the system's application and configuration, detailing how the Discfile Control 270 manages data transfer (36-bit words plus a parity bit, transferred serially) between the PDP-6 processor and the Discfile 5022, which stores data on 16 magnetic discs. It describes the physical structure of the discs, including inner and outer zones, tracks, and sectors, and explains the addressing scheme for data retrieval. System performance specifications, such as storage capacity, data transfer rates, and access times, are also provided.

A significant portion of the document is dedicated to the system's logic, covering the intricate interface signals with the processor and the Discfile 5022, command logic (including NOP, Read, Write, and Read Compare operations), and a detailed explanation of the 8-state file-control octoflop cycle that governs operating sequences. Data logic, including bit-by-bit transfer, parity generation, and address transmission, is thoroughly described. The manual also addresses alarm and error detection, outlining various error-status flags and priority interrupt conditions.

Beyond operational aspects, the document provides extensive guidance on maintenance, encompassing preventive maintenance schedules, adjustment and calibration procedures, diagnostic programming examples (e.g., using MAINDE C 670), and a detailed list of recommended spare parts. Furthermore, it includes instructions for installation and preoperational checkout, covering site selection, unpacking, cable connections, power controls, and initial system verification. The document is supplemented by a comprehensive signal glossary and a guide to understanding the accompanying engineering drawings, which are crucial for detailed technical reference and troubleshooting.