TU58 DECtape II Technical Manual

This technical manual provides comprehensive information for the installation, operation, programming, and maintenance of the Digital TU58 DECtape II, a low-cost, random-access, fixed-length-block mass-storage tape system.

Key aspects covered include:

• General Description and Specifications: The TU58 uses preformatted DECtape II cartridges, storing 262 kilobytes of data in 512-byte blocks across two tracks. It features a compact design, a single-puck drive mechanism, and a microprocessor (8085) that manages tape handling and communication, reducing the host system's load. It supports one or two drives, though only one operates at a time. Performance specifications include data transfer rates, access times, and data reliability (e.g., 24 kbytes/s, 9.3s average access). It also details electrical, mechanical, and environmental requirements and available configurations (e.g., rackmount TU58-CA, component modules TU58-AB/BB).
• Operation: Instructions on controls and indicators (like the run light), cartridge loading, unloading, storage, and care (including use of the write protect tab). It provides guidance for routine maintenance, such as cleaning the head and motor puck, and includes a trouble isolation chart for common operational issues. Procedures for rethreading damaged tape cartridges are also detailed, primarily for data recovery.
• Programming: A programmer's guide to the high-level command set and the Radial Serial Protocol (RSP) used for host-controller communication. This includes descriptions of message packets (command, data, end messages), flag byte op codes, and specific instructions (e.g., Read, Write, Position, Diagnose) with their parameters and success/error codes.
• Installation: Comprehensive instructions for mounting the TU58-CA rackmount version, power selection (110/220V), and general drive/module installation. It also covers selecting and setting up interface standards (RS-422/RS-423 compatibility with RS-232-C) via jumpers and performing an operational checkout.
• Options: Discusses adding a run indicator LED to show tape motion and the functionality of a boot switch for program loading, particularly useful with LSI-11 systems for unattended operation.
• Technical Description: Provides in-depth details on the internal workings, including block diagrams, data flow paths (tape to interface and vice-versa), tape motion control, velocity control, head selection, write and erase circuitry, data encoding (ratio encoding) and detection, serial/parallel interfaces, and the microprocessor's role with its memory (ROM, RAM), I/O ports, registers, timer, and firmware operations.
• Maintenance: Focuses on Field Replaceable Units (FRUs), offering a detailed troubleshooting chart for service technicians and procedures for removing and replacing drive parts (e.g., tachometer encoder wheel, microswitches) and power supply components.

The manual is intended for users, programmers, and service personnel, providing all necessary information for the effective deployment and upkeep of the TU58 DECtape II system.