RP02 MRX 660-1 Schematic

This document provides a comprehensive technical overview and detailed schematics for the control system of a disk drive, likely a DEC RP02 model, focusing on its operational logic, electronic design, power distribution, and timing.

Key sections of the document include:

1. Operational Logic Flow (Page 1): A detailed state machine or flowchart outlining the drive's control sequence. This includes:

   • Power-up Sequence: Initializing the drive and checking essential conditions.
   • Head Positioning/Seeking: States for reverse, forward, detent, and zero velocity seeking, along with "Compare Test" and "Count Cyl" for cylinder positioning.
   • Drive Readiness & Control: Transitions to "Ready" state, a "Restore Loop" for recovery, and error conditions like "Seek Incomplete" that trigger an "Attention" signal.
   • Timers: Explicit mention of various delays crucial for operation, such as Pick Delay, Ready Delay, Seek Incomplete Delay, and Forward Seek Delay.

2. Detailed Electrical Schematics and Block Diagrams (Pages 2-33): The bulk of the document illustrates the electronic implementation of the control system, covering:

   • Logic Assemblies: Schematics for key functional blocks like the Servo Sequencer, Adder/Speed Decode, Cylinder Present Address Register (CPAR), Head Select Register, Control/Safety logic, Write Logic, Read Amplifier, Transducer Amplifier, and Index/Sector control.
   • Power Supply and Distribution: Diagrams detailing AC and various DC power supplies (+5V, ±15V, ±36V, +24V, +55V), power distribution, and power fail monitoring.
   • Actuator Control: Circuits for actuator drivers, which control the physical movement of the read/write heads.
   • Interconnections: Wiring diagrams showing how different sub-assemblies, boards, and units (e.g., interunit control harness, unit input, interior control panel) are connected.
   • Support Systems: Schematics for lamp drivers (for status indicators) and various delay timers.

3. Timing Diagrams (Page 34): Illustrates the temporal relationships of critical signals for operations like index and sector detection, "up speed" timing, and cylinder transducer counts, vital for precise drive control.

In essence, the document serves as an in-depth engineering reference, detailing both the functional states and the underlying electronic circuitry of a disk drive's core control mechanisms.