CR11/CM11 Card Reader System Manual

This document is the CR11/CM11 Card Reader System Manual, published by Digital Equipment Corporation (DEC) with editions from October 1971 to July 1975.

It describes the CR11/CM11 Card Reader System, a peripheral designed to interface with the PDP-11 family of processors to read punched or marked Hollerith data cards at rates up to 600 cards per minute. The system consists of two main components:

1. The Card Reader: A motorized unit (compatible with Documation and GDI models) that reads 12-row, 80-column EIA standard cards.
2. The CR11 Controller: A DEC interface unit that connects the card reader to the PDP-11 Unibus. It manages data transfers, provides a 12-bit (standard Hollerith) or 8-bit (compressed Hollerith) output character, monitors reader operation, and issues control commands.

The manual provides comprehensive information for users and maintainers, covering:

• Introduction and Specifications: Overview of the system, its components, and technical specifications for the controller and various compatible card readers.
• General Description: Detailed explanation of system operation, the card reader's functions, and the CR11 Controller's role.
• Operation: Procedures for normal use, including controls, indicators, card handling (loading, unloading), error correction, and steps for both off-line and on-line operation.
• Programming Information: Details on device registers (Status, Data Buffer, Maintenance), interrupt handling, and a programming example for software control.
• Theory of Operation: In-depth description of the CR11 Controller's internal logic, including address selection, interrupt control, status register functions, data buffer, and the data encoding network.
• Appendices: Additional details on GDI card readers, card reader interface signals, Hollerith code, and integrated circuit descriptions.

The manual's primary focus is the CR11 Controller, providing the necessary information for understanding system operation and diagnosing trouble symptoms, rather than detailed component-level troubleshooting for the card readers themselves.