RX8/RX11 Floppy Disk System User's Manual

This document is the "RX8/RX11 floppy disk system user's manual" (EK-RX01-OP-001), published by Digital Equipment Corporation in November 1976.

The manual describes the RX8/RX11 Floppy Disk System, a low-cost, random-access mass memory device compatible with IBM 3740 equipment. The system consists of an RX01 subsystem (comprising flexible disk drives, read/write electronics, a microprogrammed controller, and a power supply) and a host interface module: either an RX8E (M8357) for PDP-8 systems or an RX11 (M7846) for PDP-11 systems.

Key functionalities include storing and retrieving up to 256K 8-bit bytes (or 128K 12-bit words) on preformatted flexible diskettes, performing implied seeks, automatic head position verification, and hardware Cyclic Redundancy Check (CRC) operations. The document details the system's physical components, its "double frequency" recording scheme, and its IBM-compatible logical format (77 tracks, 26 sectors per track, with distinct header and data fields).

The manual provides comprehensive information covering:

• General Information: Introduction to the system, its physical description, components, and compatibility with IBM 3740, including detailed specifications for reliability, drive performance (capacity, transfer rates, access times), and environmental characteristics (temperature, humidity, magnetic field sensitivity).
• Installation and Operation: Guidelines for site preparation (space, cabling, AC power), environmental considerations, unpacking, physical installation steps, and crucial operator control and diskette handling practices and precautions for storage and shipping.
• Interface Programming Information (for both RX11 and RX8E): Detailed descriptions of device registers (e.g., Command and Status, Data Buffer, Track/Sector Address, Error and Status registers), various function codes (e.g., Fill Buffer, Empty Buffer, Write/Read Sector, Read Status, Read Error Register, Power Fail), programming examples, potential restrictions and pitfalls, and error recovery procedures with specific error codes.

The document emphasizes the importance of adhering to environmental and handling guidelines for the diskette media to ensure data integrity and system reliability.