DECtape Control Type 550

Summary:

This manual provides a detailed technical and operational description of the DECtape Control Unit Type 550, which is designed to serve as a fast, reliable input-output device for PDP-1, PDP-4, and PDP-7 computers.

Key sections of the document include:

• System Overview: An introduction to DECtape, highlighting its flexibility, speed, and reliability. It explains that the 550 Control Unit allows for word-by-word data transfer, distinguishing it from block-transfer systems.
• Applications: Descriptions of various uses for DECtape, including program and data storage, system editing, on-line system data handling, multiple-user random access, and data sampling.
• Specifications and Features: Technical data such as word transfer rates, block sizes, and power requirements, as well as features like bidirectional reading/writing and Manchester polarity-sensing.
• Format and Operation: An explanation of the track layout (timing, mark, and data tracks), how "prerecorded" tracks function, and the three main modes of programmed operation: search, read, and write.
• Theory of Operation: A detailed look at the logic circuits, including window registers, timing pulse generators, error detection mechanisms, and how the computer interacts with the control unit via IOT instructions.
• Maintenance and Programming: Guidelines for preventive and corrective maintenance, including testing procedures and tools, as well as a list of available subroutines (such as Microtog and Microtrieve) and an instruction list for interfacing with the supported PDP computer models.