Part 8

Summary:

This document serves as the technical documentation for the RK8-E Disk Drive Controller, which interfaces with the PDP-8/E OMNIBUS and supports up to four RK05 Disk Drives.

Key sections of the document include:

• Purpose and Function: The RK8-E acts as the controller that decodes IOT instructions, manages data transfers (via single cycle data breaks), handles CRC generation/checking for error detection, and provides status flags.
• Physical Description: It is composed of three quad modules (M7104, M7105, and M7106) installed on the OMNIBUS.
• Recording and Formats: The system utilizes double-frequency recording. It details the sector format, including the preamble, header (cylinder address), data words (256 12-bit words), and CRC character.
• Registers: Descriptions of major registers are provided, including the Command Register (operations/unit selection), Current Address Register (memory addressing), Disk Address Register, and Status Register (error and condition flags).
• Operation and Programming: Provides a detailed guide for programming the controller, including specific IOT instruction sequences for tasks like formatting a cartridge, performing read/write operations, seeking, and recalibrating the drive.
• Theory of Operation: Contains a breakdown of the controller's internal logic, including the I/O bus interface, control sequencer (major states), data buffer registers, and CRC computation logic. Extensive signal lists for inter-module communication are provided in tables.
• Maintenance: Includes diagnostic programs for troubleshooting and a comprehensive list of recommended spare parts.
• IC Descriptions: Provides technical specifications and logic illustrations for specific integrated circuits used within the controller (74155, 74193, 7485, and 74161).